The latest Taranis transmitters & X series receivers have the EU compliant firmware, this means those old X series receivers need a firmware update to work with the new transmitter, and old transmitters require a firmware update to work with the new receivers.
I have an old transmitter, and when I got some new EU compliant X8R receivers I simply loaded the non-EU firmware to them and all works just fine.
FrSky's new transmitter, the Taranis X9D, continues to generate great interest. I've acquired one from t9hobbysport, and all I can say is its fantastic. Programming it is a bit different than Futaba/JR/Spektrum, thought Multiplex users would find it very similar. I'll have it up at the field at the next available opportunity, and will gladly help anyone who buys one to program it.
The 8 channel telemetry receivers X8R cost about €30 (ex delivery), and compare very favourably to the considerably more expensive big brand counterparts.
Non-telemetry receivers such as the new FrSky V8FR-II 8 are even cheaper, and are Taranis compatible in 8 channel mode.
This is an excellent replacement for the stock NiMh, although the more recent radios come with a 2000mah LSD battery which lasts all day.
FrSky Taranis - review and photo gallery
Available from t9hobbysport