Oh I bet there are far more FM3s out there, or will be over time, than Axe-Fx IIIs, just because of the price point. And I know that FM3 presets were supposed to work on Axe-Fx III (and do).
It's not unprecedented - I took the same approach to making the Dream Rigs - it was developed for the AX8 and took advantage of all the hot switches, then I ported into the Axe-FX XL, then I went through every single preset and adjusted for the firmware difference (ARES 2.0 versus Q10.01 on AX8. So this is not dissimilar. When you are dealing with 1000+ presets and multiple units, efficiency of work flow is key to keeping up!
Last - part of the intent for me is to get the sounds into as many hands as possible, because (I hear this over and over) - "your presets really woke up my Axe-Fx/AX8/FM3, I wasn't fully sold on it until I got your presets and found the sounds I have been looking for." I want people to love these units as much as I do. For guitar players, having the Axe-Fx makes everyday like Christmas (quoting Steve Vai!).