You may want to read this article on Roller vs Flat Tappet Cams and Lifters.
Flat Tappet Cams vs. Roller Cams - Lunati Power
When I recently had my FE 428 refreshed, I went with Roller cam and lifters and rockers. The quick responsiveness of the engine is clearly noticeable. It just seem to have an eagerness to gain RPM. Perhaps this is the less resistance, but I really do not know.