I have an HVX200A. Sooner or later I'm going to need a second camera. If I bought the HMC40, what kind of problems would I run into mixing the footage from these cameras on the same FCP timeline?
Also your HMC40 would have different DOF characteristics due to 1/4" vs 1/3" sensors. Colorimetry should be in the ballpark though as it seems to be with all Panasonics cameras. Much easier to match to disparate Panasonics than a Panasonic with a Sony or JVC.
Learn to use Color really well and I bet you could get them to match pretty closely with good lighting. It's all about the lighting.