FWIW, I use the X36F (USB) version, and have all the keys mapped to various things.
Haven't had a problem yet, and I use the thumb knob (which it sounds like, to me, as the chummy being referred to) for aileron trim without seeing any interference with other controls - it works great, I highly suggest it, if you're not using combat trim.
(Combat trim, yuck, ick ick)
Cheers