My confession:
My babies have both been really large, strong kids........and when they fell asleep on their tummies, I let em stay. Even as newborns.
My feelings on it were that a large part of the fear involved had to do with babies who couldn't turn their heads. But both of mine were able to hold their head up from birth. Also, I never sleep far from them (we co-sleep) and I'm careful about the surface they sleep on.
This time around, my midwife actually suggested letting my son do it sometimes to help sooth a gassy tummy. And she said the exact thing I'd been thinking........that since my baby was so strong, there was a significantly lower risk for him.
All that said, I generally only do it if I can nap or sleep with him, because I am still a little paranoid.