I just saw some for the first time the other day - I haven't ridden for quite a while, and even then it was only fire trails...

They look very interesting, but I am a little suspicious (although my experience extends to SPD's only) about the ease of location for novice riders, such as myself. Clipping back in after getting/falling off is always awkward for the less experienced, and I think I would stay with my, albeit heavy, platform SPD's for now. If I become really hardcore, and lose like maybe 3 stone in weight (I am a spectacular 15st/96kg) I may go for some...

Duncan