'Wide band' receivers are the ones that have problems, not narrow band. Even with the RFFS, a 'wide band' receiver, you can fly with other models. A couple of channels on either side should be vacant, and the harmonics of transmitters about 6 channels apart may cause some problems. I fly with others and generally have no problems with a half-dozen transmitters on at the same time.

The JMP receiver is narrower band than the RFFS. If you get one of these, spend the extra money for the plug-n-play version with the sockets already attached unless you are comfortible soldering very small electronics.