Well... What I do to bench (I feel that I use a lot of leg drive). Is this. I setup and plant my feet out and wide on the floor. When I push, I ground them HARD, but keep my hips and shoulders planted, while maintaining my arch. I find I have so much more power this way with a stable base to "push through" I really don't understand the dudes that hold their legs up in the air while benching... Only thing I can see that it does is prevent them from shooting their hips up in the air and unsafely arching... but if you have to lift your feet up to do that, you should really be looking at your bench form IMHO.