ORIGINAL: Bax
We'd not know of any modification or "upgrade" to make a Futaba tranmitter compatible with a non-Futaba receiver. If a transmitter was sent in to us where the user complained that it didn't work with their non-Futaba receiver, we'd make sure the transmitter operated correctly per Futaba's specs. If the customer's non-Futaba receiver still didn't work with the Futaba transmitter, it's not Futaba's problem.
We don't know whether the 9C synth module will transmit the same non-standard encoding pattern as the Spectra module does so it's unfair to criticize Futaba in advance -- but it's very interesting to compare Futaba's definition of "support" to that used by other vendors who often consider the slightly larger picture when attempting to deliver customer satisfaction.
It also makes good sense, when you're trying to sell customers receivers based on outdated (non-DSP) designs, that you don't go out of your way to make your transmitters compatible with more advanced designs from other vendors.
Every time I think I've decided what new transmitter to buy, various vendors keep coming up with reasons (usually attitude-based) why I shouldn't consider their products :-(