transmitter for excavator?

[RCP57]

I really like my DX8 but wish it had the sliders like on the DX9 for the tracks. Someone told me recently that the newest(or if you upgrade the firmware on the older ones) Spektrum radios will no longer work with Orange RX receivers. Anyone else heard of this? I have been using Orange RX receivers with my older DX8 with good success and they are easily 1/5 the price of OEM. I have thought about upgrading to the DX9 but it would be very costly if I had to upgrade all the aftermarket receivers too!

Thanks