Well, I've done the mod and didn't get the best results. Before the mod my RX7 MS got a crapy 3-4m range. Now I get about 8m, which is not bad but not what I was expecting.
See the pic below for the mod. I had to remove pin 9 on the TX chip from the pcb to be able to isolate the power from the rest of the board. This was a bit dodgy but it worked.
Here is a (fuzzy) closeup of the mod. I haven't implemented the charger side of the circuit just the reduced 5V rail to the TX chip. I think I blew the Zener diode, during testing it wasn't dropping the voltage by 6V as it was meant to.
Whilst I was at it I removed the stock antenna and replaced it with some fine enamled wire that was spiraled twice over. This added about 2 meters to the range. The wire in the pic is moving when I took the photos so it looks like two wires instead of one.
Back to the drawing board..............
ph2t.