I agree that the faster you can go, the more confident you are. That's why I often don't ride unless I feel up to the task of sprinting when I have to. On the same note, it's why I won't ride with anything other than my stiff-soled road shoes because I can't sprint fast (or what passes for fast w/ me) with my casual cycling shoes as they just turn to mush when I stand on the pedals.

I think that if the OP got a road bike or at least made his ATB faster by losing the suspension and adding slick tires that he would feel more comfortable on the road as he would be faster. That's not to say that one can't go fast on an ATB but it takes a level of fitness that I think most of us just don't have (translation: a level of fitness I don't have ).