I bought a FGR4B receiver so I could use the "enhanced receiver" mode and get the SR/SFR frequencies out of the radio, this sets the PWM frequency to 833 and 1000 respectively. None of my servos could handle the SR/SFR setting, they all go herga derga and will not respond to input or they start spazzing out. I tried both Tekin and Protek without any success. I plan on getting an MKS that can be programmed from the radio so that I can fully eliminate any possibilities of incompatibility. I'm not ready to throw in the towel on the NB4 but the Sanwa radio simplicity is starting to look better and better. If a US vendor had the FlySky servos it would be different, I might harass my local hobby shop this afternoon and see if any of his suppliers can get one of their servos. Unfortunately, the only market I can find the in servo is in China.

I did find another setting in the manual that can "reduce latency" and that's by putting the receiver in a 1-way bind. This does not transmit data back to the radio, you lose the receiver's telemetry which to be honest is fairly useless for on-road racing. If I was flying/boating and had a fuel gauge or voltmeter I could see needing the benefits of 2-way but I don't look at my radio between the horn going off and the end of a race. I'm going to be at practice again tonight, while I'm not gaining much traction hopefully there's something to take away from all of my testing. I do believe the radio is a very great option for a mid-class radio system at the moment. It might get better if we can find the right combination, it's just trial and error at this point.