Of course it hurts more on concrete than SnowFlex. Check out this video
of my friend Ben bailing on a corked 5 (snowboard) - if that had been on concrete (or indeed ice), he would have fucked hiumself up pretty badly. He did bust his knee on that one though - he thinks he caught it on a sprinkler head. And he says his wrist is weak now from falling on it so much.