RE: On board Data Terminal
We've flown several jets with an onboard data system that we developed that interrogates the JetCat ECU for the same data that a data terminal does and telemeters it to the ground. We've never had any interference problems with Futaba and Spektrum 2.4 GHz receivers. Also, I believe that EagleTree has an add-on that does the same thing.
Back in the 72 MHz days, you had to check carefully that any onboard processors would not cause interference problems - mainly because their clock speeds were right around the 50-100 MHz range. Now that we've gone to 2.4 GHz, the issue has mostly gone away.
Assuming you're on 2.4, do a thorough range check and if is OK, I'd fly it.
Bob