I think I know the answer, but just want to confirm.
Are all RF2 devices (e.g. XD-V35/55/70*/75, and Relay G30*/50*/90*) compatible with each other?
Note* - Assuming older devices have been upgraded to 2.x RF2 firmware already
I pretty sure only limitations would be what channels are available (on a given device) & encryption (only available on devices that support it).
For example you can use any RF2 Relay G30/50/90 transmitters & receivers with any XD-V35/55/70/75 RF2 transmitters & receivers.
Is that correct?
Yes, you are correct