I have a pair of 8mm Leadville pacers from LunaSandals. I feel they are too thick for most running, my new advice for sandal running is "Start Thin"! In taking my own advice, the original Lunas are 6mm and offer much more ground feel. I took these on a very challenging trail run this weekend (through hurricane Irene damaged trails). Sadly Leather separating from the Luna's foot bed. Went through many puddles and mud on a long trail run. Seems the leather changing shape over powered the glue that was holding it. I will smear either bathroom caulk or gorilla glue to re-adhere the leather down to the rubber. When these layers are separated the gap will hold mud and debris. They are now classified as "in need of repair". The original Luna is available here.