Could it be a problem with your feet, ankles, legs, etc instead of the shoes? I ask because I can actually feel when the nerves in the ankles and feet get pinched and then my feet go to sleep. It's usually at about mile 25, and it doesn't get any better until I get off the bike and do some stretching. I've been in PT for tight calves and plantar fascitis, and one physical therapist gave me some stretches for the nerves in my ankles and feet. Since I've been doing the stretches regularly, I've noticed that my feet go numb less frequently... just an idea to consider.