Hi Julian,
I put together all advantages of UFX+/II in my blog in the following article:
https://www.tonstudio-forum.de/blog/Entry/68-RME-UFX/
You will find that besides enhancements in the analog section of the device also other useful changes have been performed.
For the UFX II (was announced later) everything of the UFX+ is applicable minus USB3, TB, MADI.
I owned the UFX, upgrade to UFX+ and can't complain.
Up to you whether you regard the upgrade as important.
You should consider upgrading to UFX+ to have more options not only regarding scalability / upgrade possibilities through MADI, but also to have two options to connect to the PC (USB3 and Thunderbolt). Furthermore, USB2 works, but it doesn't offer enough bandwidth to transfer all channels incl. MADI. In other words, with USB2, you can use the MADI channels only for local routing on the UFX+.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14