If you decide to go with a new radio and you only have one RX to replace you should consider Futaba's new 2.4 GHz set.
http://www2.towerhobbies.com/cgi-bin...&I=LXPZT8&P=SM
Only $220 for TX and RX. You can use your existing flight pack (check that battery too).
Use Tower discount 010HA and get $20 off that for under $200 for a new system.