if you want to blast the heck out of it DTL then either you need tiny net clearance or good amount of top, but as LeeD says, to hit a winner or a winning shot (one that sets up a winner) you just need to hit a drive or topspin with decent pace to force the issue. With good direction and relevant depth (short or long as the rally dictates). Dont stress over needing tons of top. Sure if you want to hit a dipping shot at a guy at the net and hit it where he can reach it, then lots of top to make it dip is needed.
But if you are going DTL then you dont need to stress too much about tons of topspin.