You know the point made by Tony about the uneven weight distribution from an engine and exhaust makes a ton of sense. I know Rusty Dose opened my eye's to the importance of balancing a plane on it's axis with indoor foamies. E setups are more centered and thus a lot of inherent problems would be gone.
As far as covering goes the mix of UC and Monokote is tricky. I can't remember what doesn't stick to what but there is some incompatability.
The biggest problem I have encountered with Ultracoat is that I have seen it bubble up in the direct heat on a hot day. Once it bubbles it's nearly impossible to get it to stick again.
MK seems better in the heat. The UC white however has never shown the problem and is so much easier to apply. I like the shine of the MK colors better too. Also MK is slightly lighter. Mike