I've got a Sanyo FH1 and the swing test for vertical balance fails. Even with all weights removed the initial swing from horizontal to vertical is too fast, and I get a pendulum effect when I stop moving. I assume this means I'm slightly top heavy, but not enough to invert the rig. Correct?

I've thought about using a Manfrotto Pro Rapid Connect Adapter Assembly with Sliding Mounting Plate (#3273), but I'm not sure that even that would provide the additional weight needed. TIA.

no, you're bottom heavy,
all you need to do is add some extra weight on your camera mounting plate, I had the same problem balancing Lumix TS1 on Merlin, it took me about 1 Lb of extra weight to make the rig well balanced and steady, but it flies great now.

Oops, I meant bottom heavy. Thanks Buba. What did you use to add weight?