After having the roller cam in my 350 Vortec I probably will never run a flat tappet cam again. As was mentioned, no break in time, smooth performance, etc. Lots of new cars are coming off the line with roller cams installed, including the 7.4 you are working on in the later Gen series.

I would stick with hydraulic though, no real need to go mechanical on the street unless you are going to street race it, even then the hydraulic would be fine.

Don