I use DMR v12 with 5/10s and have experienced no problems with coming off the pedals...in fact just the opposite. I have to lift my foot to change position or to dab. I tried SPDs just out of curiosity and I can see how they help to make pedalling more efficient but I don't do much sit down pedal riding except on transitions and the disadvantages for me are the god awful SPD shoes for anytime you are off the bike and the likelihood of not being able to throw the bike away in a crash...probably leading to knee or ankle injury. PS when was the last time you saw a MX rider clipped in??