As with uprights I have seen bent riders on all ends. Some get a bent because they have physical problems that don't allow them to ride an upright and this probably effects their performance as well. However, I have seen a number of bent riders who can drop uprights on flat roads with little problem. I also know that when I have ridden with these guys on their uprights they are not as fast. A bent has a lot of mechanical advantage and definite aero advantage over an upright.