With all the money these companies put into developing their respective 2.4Ghz systems, why would these companies make them or let them be compatible with each other? These are all covered by diff patents and the encoding/decoding signal technology is different enough that they can't be interchanged, using basically a cheaper diff brand rcvr with another brand's 2.4 TX.

I think some of the Losi RTR rcvrs will work with Spectrum, but Spectrum made them for Losi to begin with IIRC. Futaba went out of their way to make sure they didn't do that with their rebadged rtr 2.4Ghz systems.

HK has apparently developed what it calls an 'orange' rcvr deliberately to work with FAAST, ignoring any patent infringement. They're less than 1/2 the cost of a real FAAST rcvr. Be interesting to see who they copy next, Spectrum? Also will be interesting to see what Futaba does.