oh you will get velocity forward
swinging this way actually does not change the path that much geometrically... but allows you dump out all the energy..... and you swing more freely without worrying about smacking the shin.
you get more spin too.. and a spinny / kicky ball is just as if not more difficult for the returner to handle.... you get more safety margin and more time to rush to the net.
Edberg / Rafter - great serve/volleyers who play this way.
that Fu smash.... WOW !!