Yeah, I’ve been banging my head against a brick wall with this too for a long, long time. Hopefully we’ll get some support after the weekend.
I’m trying my imports on a simple default 2011 theme with wpec, so this thing should work out of the box. Obviously the latest plug in must have been tested which is why I’m beginning to think the 500 server errors might be something to do with my hosting provider. Are you with Go Daddy by any chance ?