RE: XPS and Giant Scale
I don't have this system and I don't fly giant scale. One tip Ihave picked up across all the MFG systems is make sure you have enough battery to the receiver to hold voltage. All of these 2.4 GHz receivers are microprocessor based. If you drop the voltage too low, they have to "reboot" for lack of a better word and that can take a couple of seconds. I think the XPS can tollerate down to 3.5V which is VERY low voltage, but you dont' want it dropping below 4, for sure.
I am sure you you have plenty of power but keep this in mind. On 72 MHz systems, the receivers seem to fade momentarily if the voltages drop too low but they don't actually restart.
I am not giving you the technical detail, just the cause and effect. Make sure you have enough power to insure voltage to the receiver.