I use a very old Sony HandyCam- analog in fact. Using 8mm, (not even Hi8) for all iMovie work. Done extensive work using both digital and analog video and merging the two. May be useful when converting different video sources and camcorders.
Perhaps this solution may work...now that Sony and Apple don't play together anymore. I use a DataVideo analog to digital converter. It is also about 6 years old now. It has a digital to digital option. I would guess that newer models are more sophisticated. The converter is not expensive- about $100. Works on all analog to digital stuff...VHS, and even cassette audio tapes. Uses standard audio/video mini plugs, and firewire connected to the mac. I started using this with iMovie 2, and a sawtooth G4. Now works like a charm in my first generation iMac G5 and iMovie 6. (also works great with G4 Mini and G3 Powerbook). I just got iMovie 8, and not yet installed it. I expect it to work flawlessly there as well.