I found out from the reading that i've done that the Turnigy/Flysky 9x transmitter can be operated using just 2s 7.4v lipo setup. Which result in no less the performance of the one with a 3s 11.1v battery. Provided you have flash your transmitter with the custom firmware ie. ER9x. This is due to the option to set your transmitter low battery alarm which you can't achieve with the stock firmware.
Because I'm cheap and I have a couple 2s lipo around, I did this simple mod to the battery balance plug so it can be used directly in the transmitter.