I seem to remember reading that on a JR 10 system, that all 10 channels are proportional, but channels 9-10 are updated at a reduced rate. It is not really noticed unless you use servos on channels 9 and 10 with servos on channels 1-8. As long as you keep all mixes on 1-8 or 9-10, you are okay. Just use servos on channels 1-8 for all primary control functions. Use 9-10 for other functions such as gear, brakes, etc. You can mix functions, as long as the ones on 9-10 are not a problem being updated at a lower rate.
I do not think there is an issue with the 9 channel systems.
Can anybody confirm these items?