You basically want a shoe that offers rock and debris protection and not much more. We have a number of clients using Nike Frees and good old Converse Chuck Ta

You basically want a shoe that offers rock and debris protection and not much more. We have a number of clients using Nike Frees and good old Converse Chuck Taylors (low-cut). Personally, I like my Converse more than my FiveFingers. (I'm co-owner of CrossFit Quantum and we teach forefoot/POSE running as part of our movements.)