Good point tjf - if you are using Futaba and other HRS-style radio systems, you do need the digital version (9650) as they won't function with the analogue one (9602). Spektrum systems work with either in my experience, the superb Futaba FASST system works with the digital one. HTH
Thanks for the info on the positioning of the Savox spindle being non-standard. That's probably a better explanation for why there are almost none in the 12th and GT10 community than any performance concerns!!