To do the calcuation correctly you need to confirm either off a Cam Doctor test or via the cam manufacturer what the .200 duration numbers are for the compared camshafts.
Again, of course if you simulate two camshafts that have basically the same lobe profile they are going to A) look exactly the same to the valve they are lifting, and B) basically make the same power.
It's as simple as that. Unless your going to take advantage of the benefits of the roller within the lobe profile there really is no reason to go roller. For the exact reasons you mentioned. Taking advantage of the roller design and lifting the valve off the seat quickly and to a high lift is where you gain the power.