I agree with everything you said, except for two things...

One, we found in our experiments with ultralight aircraft that the shielding was more effective when it was grounded on only one end; not both. This has also been my experience with model airplane ignition engines.

Also, I don't particularly recommend PCM for gas ignition engines as they can mask interference problems until it's too late. If you want to fly PCM, thoroughly test the system for glitches first with PPM.

AV8TOR