Ph1 RC is compatible with part of Ph2 RCs (those with 2.4GHz link)
Ph2 RC is NOT compatible with any higher model
Ph3 Std RC is not compatible with Ph3 Pro/Adv or any higher model
Ph3 Pro and Ph3 Adv RCs are identical - so compatible, and also compatible with Ph4 (the first model) RC.
Inspire 1 RC is compatibe with Ph3 Pro, Ph3 Adv and Ph4 (old model) - but not the other way.
For higher models - I have no data.