Through some research it appears polycarbonate is a much better thermal conductor than leather. Leather is really poor with thermal conduction. So that means that it is more likely to hold heat internally letting the phone to heat up more than it should. Has anyone had issues with this? A friend bought one for me for xmas though it's still on route. I think I may keep the polycarbonate for regular use and maybe use the mozo when going out somewhere where little heavy usage will occur.