I have been experimenting with my flysky i6 transmitter, and learned some neat things.
1) There is a secret menu
2) There is a secret way to put the transmitter into firmware update mode
3) The firmware & device is hackable to allow telemetry, thus allowing you not to require apm telemetry modules.
4) The i6 transmitter has been 'software limited' to be 6ch. It is really more than 6 (seems to be 8 right now).
If you have one of the Turnigy/Flysky i6 transmitters you can learn about these functions on my blog here:
happy to know your thoughts and experiences