As yet I haven't upgraded the internal XJT modules in either my X9D or my X9d+, both original. Both have had the bootloaders and firmware upgraded to 2.2.2, as yet I have not had any issues binding to any receivers.
Receivers I've bound are X6R, X8R, S6R, X4R and X4R-SB, as well as D4R-II, V8R4-II, D6FR, V8FR-II and V8R7-II, all have bound perfectly. I won't be getting a G-RX6, vario is not legal for competitions, I do have a plug in vario that I remove on comp days.
I have held off flashing the XJT's as nobody has convinced me it will not cause issues, and at the moment the only issue I have is a low RSSI warning on both TX's at around 250 metres range, never lost conection.
I have a couple of each R-X4R and R-X6R receivers for my gliders, as they are the only aircraft I fly at long distance. Can't test fly at the moment as I have just had a new knee installed and I'm not able to drive for a couple more weeks.
I just checked both XJT's, the X9D says XJTVER 0 and the X9D+ says XJTVER 215, both are the original firmware they came with.
Hope this is of help