Those Airtronics are solid radios. One thing with Spektrum, is that all of the BNF/PNP planes from eflite/parkzone, etc are only compatible with Spektrum, which if you have any interest in any of those or the micros, then spektrum might be worth a look. They're solid radios, nothing to worry about.

If it was me, I'd opt for the 6 channel one, or you could always look for a nice used one in the classifieds, could probably get more bang for your buck that way.