I have Falcon and Midex, but I have not modified it because I prefer to use it with TT and other computers.
The Midex works perfectly, obviously without latency (it is the characteristic of Atari and its complements), but only once I experienced some latency and even synchronization failures among a considerable number of connected MIDI devices. Everything was solved changing the version of the MROS file to a previous one.
Although it is generally recommended "Use the latest version of MROS in the Cubase program", I found this example in Cubase v3.xx regarding Score v2.0r7, in which everything worked perfectly when using the MROS that came in each version, without " upgrade".
It is just an anecdote that you do not lose anything when you try, although you have other factors that are the modified Midex and also the modified Falcon.
ST/fm/e, STacy, Mega ST/e, TT, Falcon, C-Lab MKX... and more music tools.