The Graupner SUMD is a serial protocol like Speksat and SBUS. The channels are encoded into one digital signal and there you have no latency. But we are talking ms of difference, I doubt anyone can tell the difference. Advantages of SUMD:
VS SBUS – SUMD doesn’t require signal inverter.
VS PPM – SUMD has better resolution and zero jitter while PPM has only 250 steps and always 4ms jitter.