I think it's more frightening to pull out of straps. Going fast or downhill, if by chance you unclip, at least you can just step back down and clip back in (my experience is with eggbeaters which I love, and am way happy with the sixsixone launch spd mountain shoes, they look like skate shoes). I tried clips and straps for a while and was sketching when bombing down steep hills because I wasn't confident I could get back in the straps if my feet slipped out. So I guess it really depends on your style, speed and terrain.

On a different note, I have been rocking PowerGrips upon suggestion from several BFFGs and I must say that they truly are the jam.