VFF's can be tricky as your toes have to fit VFF"s particular shape, which I am one of the unlucky ones whose toes are apparently abnormal. I also recommend Altra Adams which are easy to slip on and look relatively normal and are just as thin as some models of VFF's and thinner than others. I believe they just lowered the price on them too not to long ago also. I have the Adams and I like them but they do have their flaws. I have to have the forefoot strap loosened up (irritates my pinky toe otherwise) to the point that it's pointless for the strap to even be on there. I am curious about the Zems so if you get those I am curious to hear what you think. They are really cheap also compared to other min-shoes. Mostly I just wear my homemade huaraches if I wear footwear. They allow my feet to be closest to barefoot and my feet don't get hot and sweaty and they cost me all of 10 bucks or so to make. I have tried on the Lemings that Patrick brought up, and while they are some of the most comfortable min-shoes I have ever put on, I am not sure that they will meet your thin sole standard. They have like an air cushioning or something in the sole that is very nice, but I think it kind of deadens the ground feel just a touch. The outsole I just looked up is 6mm, not sure on total stack height though. Anyhow, hope this is helpful. Good luck finding a shoe that is right for you!