Presumably RME has not seen this or has not yet had the time to add it to the product page on their webserver. To be on the safe side, you can send mail to support and link to this thread.
MADI is not only useful for later extensions, it can also be very practical in the following cases:
- if you use TotalMix FX for creating Submixes that you want to record via loopback, in case your other I/O ports are already in use
- if the max cable length of ADAT is not sufficient to reach a preamp in one or two other recording rooms, according to the standards ADAT max cable length is around 10 m, with RME you reach up to 15-15 m. If you chain MADI devices then the multimode fiber cable may be up to 2 km between each of the devices in a chain. OM3/OM4 multimode patch cables are usually available between 0.5–30 or even 50m.
This is now speculation, but due to MADI, higher channel count and USB3 the UFX III might have a larger FPGA which might be beneficial for any potential future feature update that (in a bad case of luck) might only be feasible on the UFX III.
What I think will definitively happen is, that an UFX II gets a feature update but the UFX III not.
802 FS is maybe another device / another story, but there it is already problematic to implement Room EQ and Crossfeed.
The question is, whether this is worth for you spending the money for such things to be on the "safer side".
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14