Roller cams have much less friction on the lobes than a flat tappet cam...
Break in is critical with a flat tappet cam as the lifter and cam interface is under shear load... There is no boundary layer lubrication on the cam and lifters like there is with the crank and rod bearings.... The sides of the lifters have pressurized oil, the bottom of the lifter and lobes of the cam are just splash oil...
You keep revving your engine cold, I will wait until mine warms up...