Btw, my workflow for fast renders and no FCP glitches is to create a motion project that matches the sequence settings in FCP where it will live. Then import that motion into an FCP bin, place on the timeline, and voila, no serious rendering at all. If you update the motion project, the bit of timeline in FCP is just re-rendered and all is well. This is why I prefer over AE, albeit I have to give up some things.
Cheers,
Jigs
Phoenix Studios Nepal: A small A/V Production House in Kathmandu.