I have used a ZAP WC2 with a TM7 module since the beginning of 2009. Using a 617 RX I have found it to be rock solid with no issues to report. I use a mini tray (hold the trannie in the normal manner) to enable the tansmitter to balance without the aerial extended. One final thing, 2.4 aerial points out from the rear of the transmitter, i.e. at 90 degrees to the back, in use so a small hole has to be cut in the tray for this to protude. No problem. Hope this helps.