Hi Miguel, I think there are two levels to consider here.
1. the purely technical level, which possibilities the respective control room (Cubase vs TM FX) offers you, and
2. the user level, how the workflow suits you.

The control room and the routing in TotalMix FX give you almost unlimited possibilities at the interface/hardware level.
You can configure the routing from hardware inputs and audio from the PC (SW playbacks) for each HW output (aka submix) individually also with different levels as you like.
If you are used to using TM FX, then you have here a powerful tool which is - once understood - easy to use and gives you the best flexibility. Also in terms of switching snapshots, maybe in combination with ARC USB or even the switching of workspaces between "quick workspace select" slots. Where the 1st ten can easily be recalled by the key combination ALT-1 … ALT-0.

Using the control room in Cubase could possibly give you some functionality which is tied to the DAW itself and its features.
But this is where my personal problems with Cubase Control room start. If you are not careful, then the output level is of all sudden higher so that you get distortion, and I never really understood why. Furthermore, the handling of the Control room in Cubase is much more cumbersome for me than controlling TM FX.
For me, configuring a monitor mix in TM FX is an easy task, so that I, personally, like to skip this functionality in Cubase.

Regarding near-realtime monitoring. The feature "ASIO direct monitoring" is supported by RME and Cubase. It also gives you the possibility to route audio from HW inputs to HW outputs with near-zero latency. But I can't tell you, by heart, whether it offers you the same flexibility compared to the routing in (EDIT) TM FX.

I could think of, that depending on your personal taste, workflow/demand, experience, you will either come to the concluding
a) that for your use cases routing over TM FX gives you the best flexibility, as submix mode is easy to operate
but it could also be
b) that routing through the DAW gives you all that you need

Maybe even a combination of a) and b) for reasons that only you know because of your long experience with both ways and that you found a workflow for yourself, that the combination of both makes most sense.

There are other examples where you also need a combination of Cubase Feature and TM FX. For example, the definition of external FX, so that you can use external devices (FX, …) like a VST as insert or sent. You need to configure it in the DAW, but also require the proper routing in TM FX to make it work.

If you want a recommendation from me (personally biased), use TM FX, it really gives you the most flexibility. But take, whatever makes you happy.

That's my two cents' worth on this topic, I am interested in what other people think.