nd brings up another good point. i can't squat on a smith what i can with a bar because i'm not used to the mechanics of it. that said, there isn't a person on this planet who can bench more with a bar than they can on a bowflex. the free bar is the far superior tool, but the smith can be useful and a number of people use them with great success.
i could see a bowflex being used as a burnout move, but anyone who sits down and benches on a bowflex for your main exercise is off the team.