In reply to Yorkieboy:
(Insert all the standards caveats about "if they suit your foot shape" etc.)
As someone who's not the best on overhangs, I've found that the sensitivity of the Speedsters does seem to make a difference when trying to learn decent footwork for overhanging stuff -- I can feel much more precisely exactly where my foot is on a hold and whether I'm actively exerting force on it.
So the no-edge thing isn't a gimmick, and it can be informative.
Obviously, they'd be rubbish on slabs or anything where you need to edge on tiny sharp edges, but if you're willing to splash out on a specialist shoe for steep stuff (or you're an obsessive shoe geek like me), they're definitely worth a look.