http://www.spektrumrc.com/DSM/Produc...Receivers.aspx
-you have the SR3500?
When I bought a 3VCS and Spektrum module and receivers two years ago I THOUGHT I had to have the HRS-version since the radio can module HRS. It can also switch to PPM or PCM, but I'm not sure if it still will work with the SR3500... I have a sneaky feeling it does
but you better make 100% sure! HRS is in any case supposedly better...
The SR3000HRS DSM 2-Channel Receiver is designed for the FUT 3PK, HRS - which is the same radio as the 3VCS.
Anyways, the crappy antennas, the poor reach, re-binding, and the interference problems with Spektrum is reason enough to jump onto FASST! Snap-on coax antenna, and no problems whatsoever!
Don't know the KO systems. But I'm sure their native 2,4 GHz systems is also perfect.