I notice most pros (Sampras for example) push with only the front leg. The back leg kicks away only for balance purposes. It also depends when you start your weight transfer from your back foot to your front foot. I have been experimenting the timing of weight transfer and find that my serve is more consistent if I push with both legs. However, I seem to get more pace if I push with my front leg only. Can anybody comment on this? Just wondering how you guys are doing when serving with platform stance. Thanks!