When I bought everdrive x7 it was also for add some personnal code on it, but fm synthesis sound definitly really hard to code... maybe some day...
About deflemask, I love the possibilites we can do with it, I used it for one song on my ipad. But I couldn't find a way to use it with a gamepad and working with touchscreen or with keyboard and mouse is bad for me, I really love gamepad ergonomics for make music.
Right now, for me the best solutions I found is use LGPT on raspberry pi, and controlling megadrive with genMDM and CC's in LGPT. There is just a little delay (milliseconds). Otherwise it's fine and if record lgpt samples + megadrive separatly can remove this delay.
But if someday your tracker could work with my everdrive then it will be also very cool, it will offer others possibilites and different working approach which is very interesting for me... I don't really can explain why but i'm not very found of using emulators like blastEM when I know I can use my real megadrive instead.