RE: Worth Converting my JR 347 to 2.4???
you might also consider what the cost of new batteries for old radio equipment will do to your costs. If you haven't used them in a while, it would probably be money ahead in the long run to replace batteries.
That said, I have a Spektrum 2.4 module that I've used in a JR 9303 transmitter, and I hear that Hitec is coming out with a JR compatible module (current info is yet this month for the arrival) that enables you to use the new Hitec 2.4 receivers with the module and a JR transmitter. I'm looking forward to that one, the Hitec 6 ch receiver is only about 45-50 bucks, vs. 90-100 for the Spektrum or Futaba 7 channel guys. I figure I'll experiment with the Hitec stuff maybe over the winter / next spring.
I've had good luck with the Spektrum AR7000 7 ch receivers and the module or the Spektrum DX7 transmitter. Keep reading forums and learning, you may be doing what I did and swap to 6V batteries in the airborne equipment when you swap to 2.4GHz also. There have been some issues with low voltage brought on by things like high current digital servos, etc, and the 6V battery is pretty inexpensive insurance when flying new radios with computer chips everywhere you look..