I've tried a few different auto-tracing applications and the one I found that worked the best was Vector Magic but even then the result still required editing.
I can generally hand trace a bitmap quicker and certainly more accurately than any of the auto-tracing applications I've ever used. Saying that though, I've never tried ImagaroZ so I would have to reserve judgement on that.
In any case, the OP said he was looking for something better than CorelDraw and Flexi. Maybe CorelDraw and CoCut would be somewhat better as they're both from Corel and they work well together. I know quite a number of
sign shop graphic designers and the majority of them use CorelDraw and I don't know that any of them use any kind of auto-tracing software, not even the trace feature in CorelDraw.
If I ever run across an auto-tracing application that can do a better or quicker job than I can hand tracing then I would probably purchase it and use it regularly. So far I haven't found anything suitable.
Dan