Berm,
OEM roller lifters are hydraulic rollers.
A hydraulic roller lifter stays in contact with the cam lobe at all times.
A solid roller lifter is bounced off of the lobe because of valve lash. The needle bearings take a shock load in addition to valve spring pressure.
If you're wanting to keep the horsepower of a roller cam along with no maintenance, you can switch to a hydraulic roller camshaft.
For the Cobra community, I have no trouble recommending a solid roller cam (with pressure fed lifters). Most Cobras don't see a lot of miles per year.
Flat tappet cams used to be an option years ago with
oil additives were in their prime, but these days, you're taking a great risk when you go to break in a flat tappet cam. Not only do you lose horsepower compared to a roller lobe, but you risk wiping the lobes off the cam and scattering metal throughout the entire engine, which necessitates a rebuild.
I won't build an engine without using a roller cam.