Well I do not know anyone who personally had an older performance engine fail, but I have read of claims that they have on the net. May be true - maybe not.
As for this convex lifter thing, the engine, my son had the intake off of, had the bottoms of the lifters flaired out, and we could not pull them from the top. I guess I'll have to stop at an auto store with a straight edge. Everyone I have talked to tells me that lifters are flat on the bottom. Since the earth was once thought to be flat, I'll keep an open mind until I know the facts.
If all the "cam break in" is about is getting plenty of
oil on it ASAP to prevent wearing through the hardened surface on start up, then the first time you let the engine set a couple months, it will fail on the next start up. I'm sure the idea is to keep a film of
oil between the lifter and the cam lobe at all times. If this happens then there should not be any wear to speak of. If it doesn't happen, I doubt much of anything can be done to prevent a failure.