jetfixr,
My first gasoline engine-powered model (It was also a WH Edge) caused much grief at first also. On it the rudder servo was glitching a lot. And, at times, some or all of the others would glitch also. This was only with the engine running.
This airplane has a ZDZ 50 in it. The choke and throttle servos are both linked to the engine with metal pushrods using plastic clevises at the carburetor. The choke and throttle servos are inside the engine box, a few inches (two or three) behind the engine. The ignition box is mounted to the outside of the engine box, as is the ignition battery.
The radio in it is an FMA FS-8 receiver (with the lighted, external annunciator that indicates losses of the rf link from the transmitter to the receiver) with seven Hitec servos. The receiver is mounted to the aft side of the wing tube that runs through the fuselage.
I found three problems that were causing all of the glitching:
1. The engine had a non-resistor plug in it. When I found that I thought my problems were over. Not so. Changing to a resistor plug made no difference. Although, the resistor plug is still in the engine.
2. The switch in the ignition circuit was intermittently emitting rf noise. I found this by eliminating the switch from the circuit and running the engine. That switch was the source of most of the trouble.
3. Gasoline engines seem to vibrate a lot. ANY vibrating metal-to-metal contact will cause interference. You must be certain that every metal-to-metal contact point in the airframe is tight and not free to vibrate. As an aside to this, I have found that if the annunciator on the FS-8 ever indicates any loss of signal it means that something is vibrating in the airframe.. Also, as an aside, in this particular plane the bolts inserted from the inside of the fuselage to hold the wings on have a tendency to vibrate loose. They will do this regardless of the used of lock washers or how much force is used to tighten them.

Before the switch was determined to be the cause of the rf noise I looked at everything else. I had replaced servos, sequentially disconnected servos and linkages, tried different receivers...you name it! I had done everything but bypass the ignition switch! It was a tedious and discouraging process. However, now the airplane is fine to fly, nothing glitches in flight, and on the rare occasion that the receiver tells me there was an interruption to the signal I know to look for something loose. This is with a non-PCM 72 mHz receiver.

For me, the learning curve for gasoline-engined airplanes was very steep.

I certainly can not speak for other engines and ignition systems but, for this airplane, neither the proximity of the servos to the engine or ignition system nor the use of metal pushrods made one bit of difference to the behavior of the radio system.

Good luck with your airplane...the large ones really do fly better.

PS: This was being written while the previous two or three posts went up. If you have a leaky ignition system that would sure do it. That was my first thought when the problems surfaced in my Edge.