RE: Exponential setting on TX?
The bottom line is with the four majors (JR & Spectrum are the same for this purpose) is:
Airtronics and JR use positive expo for soft center.
Hitec and Futaba use use minus expo for soft center.
This is important to remember if you happen to use a mix of the two which I do with one JR, to avoid an occassional wild ride on a maiden.
John