I have a friend with the front brake only and she does not skip or skid. No problems for her but NYC is fairly flat (not counting the bridges). I have seen people on NJS frames running a freewheel with both the front and rear clamp on brakes so I guess people are trusting the stopping power. There is essentially a limit type screw that braces the brake itself if it were to push back toward the fork crown. I think most people stick one of those little felt adhesive circles on the fork crown to prevent the screw from digging in.