As I mentioned, I wouldn't use DAW mode, its silly.
You can perform the same routing like in DAW mode with the normal "Full mode".
There are even Functions in TM FX which create such a routing with one or two mouse clicks on the fly.
But you still have the flexibility of TM FX if a special demand arises for you, where you do not want to route audio through your PC with the full RTL.

Also, to consider that DAWs have their own way of distributing load across different CPU cores.
If I remember right, Apples Logic Pro had the issue that the first two CPU cores tend to get a much higher load in certain project scenarios, that I do not remember exactly any more.
But what I remember that this was a limiting factor. If the load on these two CPU cores / threads became too high, then you got issues / limitations / audio drops, where the rest of the cores with much lesser utilization didn't help at all any more. As nice as many cores are ... look that the single thread performance and base clock is high too and take care for good cooling so that heat doesn't slow down the system.
I would still recommend to use desktops and no laptops for challenging workloads.

There are still a few differences. Converter latency (especially with more recent converters) is on a much lower level compared to the latency to the PC (RTL) over whatever transport you use (USB, Firewire, TB, PCI/PCIe).

And here the newer MADIface driver supports down to 32 samples at single speed like the HDSPe driver for PCIe based products. This is again 16 samples less in the audio path. For comparison, AD and DA converters have 5-6 samples.
You can make good use of it for rare cases when you really want to get lowest latencies (if the project allows).

An additional bonus: the (newer) MADIface driver supports many products: MADIface XT / USB / Pro, Fireface UFX+ / UFX II / UFX III, OctaMic XTC, ADI-2 Pro/AE/FS/DAC, ADI-2/4 Pro, Digiface USB / AVB / AES / Dante / Ravenna.

This makes it possible that the application (which can only load one audio driver at a time) can have direct access to all of these devices connected through USB at once over the MADIface driver. Windows: and this without creating an unsupported / "bogus" setup because otherwise you would have to use ASIO4ALL. Apple has here aggregate device.

Being able to access all devices through USB is beneficial in situations, where you have multiple devices but do not have ADAT ports free to route channels across devices (if they are not all accessible through USB because of different drivers).

In my setup, the applications (DAW/music player) can access all ports of UFX III and ADI-2 Pro FS R BE (8 ports in multichannel mode) at once over USB. The devices only need to be clock synchronized (through ADAT). If I need the ADAT ports for connecting other devices I can only use AES to connect the ADI-2 Pro. Then it is quite usefull to be able to access the 8 ports of the ADI-2 Pro through USB without having to sacrifice one of the ADAT ports.

There is only one advantage of the old USB driver, it still supports the pitch function, which is not possible anymore in the USB transfer modes being used by the MADIface driver.

There are some other reasons why I would still recommend UFX II or UFX III over an UCX II.

1. getting two excellent headphone outputs instead of only one
2. as you mentioned already on your own: getting two ADAT ports, which are needed to connect either two 8 port Mic preamps or to record with one in double speed
3. getting four Mic/Inst/Line inputs, where the Inst input has a wider gain range which is useful for connecting guitars
4. in my advanced stereo setup for recording guitar (which makes plenty of things possible) I am glad to have the extra analogue ports that the UFX III gives to me. With an UCX II, I would have run out of channels much earlier.
5. never forget, the analogue ports that your device already has are all available at any sample rate without loss of channels like in ADAT/MADI due to port multiplexing to achieve the needed extra bandwidth for higher sample rates.
6. the extra MADI channels can also be useful for additional submixes and loopback recording
EDIT1:
7. UFX II/III have dedicated ports to connect USB Stuck for DURec and the ARC USB, with UCX II this is sadly shared, not so well for standalone operation
8. UFX III: two ADAT ports that can be switched to optical SPIDIF
9. UFX II/III: 2x MIDI I/O which can be useful to split remote control of RME environment and accessing/controlling MIDI devices
10: UFX III: MADI allows better placement of environment across rooms (up to 2 km between each of the devices in a serial chain, do you know whether perhaps your rooms change (House, Studio). MADI is excellent to dedicate lets say 8 or 12 Port Mic preamps for a separate drummer cabin, that can be located everywhere your flat or house.
11: MIDI over MADI, no need for MIDI cabling, excellent in general and cruicial if you have several rooms
12: Excellent remote control of Mic preamps with MADI and MIDI over MADI by using RME connector

I would consider that you never know your future demand exactly. Therefore, the UFX III would be the best investment because of the possibility to expand with MADI. So this is more the interface for me that you can use for the next 20 years.
MADI tech is simple, proven, dedicated for audio. RME as pioneers for MADI have a long experience with it and offer to your great gear with MADI support. The only way to expand with ease if needed.

Other aspects:
- The UFX III got (besides very fast) the proved AKM converters (AK4490 for D/A) of the ADI-2 Pro FS.
- Customers raised a feature requested to make D/A filter selectable in different products which support it
   E.g. UFX II and UFX III). This would be useful for mastering and listening to music.
   Some people have found certain preferences for certain filters, like e.g. AKM's implementation of Slow filter,
   inspired by KaiS positive reports from plenty of blind tests in his studio.
   https://forum.rme-audio.de/viewtopic.php?pid=206380

If you spend already quite a lot of money on equipment, then I think the UFX III offers you the best of all and an excellent investment protection, even for decades. Selling and buying new because of suddenly increased demands was always the pricier way, be it in the short, mid or long term.

Looking back, everything became pricier after corona, chip crisis and delivery chain problems. Therefore, I would purchase now something which is end-game for current and future setup without any further increase in price.

Furthermore, look at the world economy, trade wars, the new positioning of chip manufacturing plants because everybody is worried, that somebody occupies areas of high-tech industry that he shouldn't do, but do we know?

Also consider the time it takes, to implement all the routing again with new devices which a different port layout.
You cannot load an UCX II workspace to an UFX II or UFX III, you would have to implement everything new.

I would definitively consider UFX III if there are no big hindering reasons (price or if you would really need a compact setup).

EDIT2: See my environment. It goes rather quick to make good use of all the I/O ports even if you are "only" guitarist (but with a stereo setup and two external FX, using the UFX III as a parallel loop for the amps, etc.
The Blog article: https://www.tonstudio-forum.de/blog/ent … iii-en-de/

[Side note: lets exclude the Octamic XTC for a while in my setup, which is there for other additional purposes like e.g.: mobile recording, to record a gig or band rehearsal. I also kept it because it is very flexible in terms of port types and gives you 4x AES I/O which could be useful for some other cases.]

Quick selection of pictures and a connection diagram giving an overview of the whole setup:
https://www.tonstudio-forum.de/attachme … front-jpg/ (front of the rack, upper part without FX)
https://www.tonstudio-forum.de/attachme … -amps-jpg/ (lower part, FX and amps/mics)
https://www.tonstudio-forum.de/attachme … p-etc-jpg/ (cabling of amp related stuff and also MIDI distribution for sending tap tempo to both FX units controlled by  switch/toggle of the Roland FC-300)
https://www.tonstudio-forum.de/attachme … -0b15-jpg/ (remote control using RME connector and either MIDI over MADI or via LAN for the 12Mic as 2nd option)

Diagram:
1. current setup and connection of devices between "recording-" and "HiFi corner" and
2. the DSL router / WiFi network, to control playback of MusicBee player using MusicBee Remote on Android.
This makes your PC and the UFX III in combination with the ADI-2 Pro in the HiFi corner to a very nice playback solution for any but also High-End'ish HiFi.
3. As a result, you can use your HiFi not only for listening to music, but additionally in TotalMix FX as "Main Out B" for mixing and mastering. My high-end HiFi is quite useful for it because it is more analytical / on the neutral side and digests EQ'ing well.

With TM FX routing capabilities, use of different snapshots/quick select workplace slots
I can use the two external FX (PCM81 / 91) for different scenarios:
a) PCM 81 for Guitar, PCM 91 for Cubase
b) all PCM for Cubase
c) all PCM for Guitar
d) PCM for pc applications to add ambience and what not (rarely in use but possible)

By plugging 1-2 guitars in the instrument inputs of the UFX III I have no sound degradation.
I can record the direct guitar signal and use it for re-amping purposes.
Furthermore I can distribute the preamp signal of one amp to the two amps and use the UFX III as parallel effect loop.
I can preserve the punch of the amp, by routing the preamp signal directly to the Effect Return of both amps, the very fast converters support this perfect without any noticeably latency. FX will be added 100% wet not weakening, only adding to the sound. Useful to have extra ports to be able to connect a rack tuner.
If there would be a demand I could also change the cabling / routing to support playing / recording with a friend using two guitars and two amps in mono .. or quick and dirty, simply add his guitar (also plugged to instr input) to my audio chain including the same or other FX, one guy using PCM81 the other PCM91.

Conclusions:
I showed this to you to put an example how useful it is to plan an environment not too small.
Really a lot is possible by simply having the UFX III as a strong basement for "everything".
Expandability ... sustainability of purchase for a long time.

IMHO operational, no wins, its easier to have one TM FX instance to work with.
Also better from cabling and you get the better feature set with UFX II and UFX III, all in one rack unit.