I was originally concerned with how well the back of the heel would stay on because there is no elastic strap to tighten it around my heel but I haven't had any problems with slippage at all. The strap along the top does an excellent job of keeping the shoe on my foot. They are equally as comfortable as the Performas and definitely feel more secure.
I got the Performa Janes in size W39 because I've noticed that all my W38 pairs of VFFs are too small now for my left pinky toe and really cramp it. The W39 is the perfect size for the Performa Jane and I definitely don't feel like my foot is swimming in the shoe or any of the toe pockets.
I'll be starting Martial Arts in a couple of weeks and I'll be trying out the Performa Janes there too (if barefoot is not an option because of the gym rules or the floor is slippery). I'll update my impressions after I try them out doing some more rigorous testing activities.
Here's a sneak peak of a couple of pictures that will be included in the Living Barefoot long review, which should be online in about a month from now.
