Hi Holmberg, welcome to the RME forum.

Judging from your current FF800, the options are:
a) 802 FS
b) UFX II (if you need MADI, go UFX III)

With the 802 FS, you cannot store everything in TM FX snapshots.
Therefore, I would recommend the UFX II. Additionally, it has the richer feature set, including DURec.

Differences you can see in my Excel:
https://forum.rme-audio.de/viewtopic.php?id=35156

I would recommend selling the FF800. Why? It's old hardware, the design of FF800 is now 20y (!) old.

a) Microsoft and Apple ceased FireWire support in their OS. Some people still get it working, and as long as this is the case, sell it now to still get good money for it. If you wait for too long, it can happen that you get much lesser money for it, then the cross-financing will not be so good.

b) Converter quality: please look at this comment from somebody who migrated from an older FF800 to a more recent UFX II: https://forum.rme-audio.de/viewtopic.ph … 48#p215048. Meanwhile, we have more modern converters in the devices, which deliver in combination with the excellent analog section a sound quality which is close to expensive high-end devices. The UFX II and III have an enhanced analog section with AKM converters known from the well-known reference converter ADI-2 Pro FS.

I think it's about time to think about an upgrade.