I have a T7XC so I connected an oscilloscope to the receiver and measured several modes. The UR speed I took from another topic on this forum from a guy who has a device to show the frame and pulse width directly on a screen. Yes, probably on the lower servo frame speeds it is possible that the transmitter transmit in a higher framerate as a kind of error correction. I did read transmitters can do this but I can not tell if Futaba is doing that and I doubt with SR/UR this is done, a lower transmission speed of data also needs a smaller bandwidth and so gives a better range.....