We use DX6i's and Botbitz on both our machines. As I said before, the only issue we have is that it goes faster one way than the other.

The mixing is set to Elevon. We have one channel reversed as I prefer to wire up my motors so that I have the positives on the same edges as the motors so It makes it easier to see the flow of power through the machine.

The Big Nipper guys messed with my TX at GSL to sort the speed issue with Conker but that was it, Speed only.

Try rebinding the RX with everything reset to defaults then edit from there. If you edited before had then it could have given the RX and ESC's false centre points or something... no idea really, just a thought.