I have a Pfaff Creative Vision and Passport. The Passport is the little portable one. It doesn't have the automatic thread cutter, but my CV does and I've never had a problem with it. Before I got my CV, I had the QE4.0 and never had a problem with the cutter either. I use the Creative Sensations regularly at classes and I've never had a problem with the thread cutter on them either.
It sounds like that's a feature you should definitely try out multiple times before you buy though so you won't be worried.