Difference between heads hyd flat vs roller

I run my squishys at near-zero preload, so if or when they pump up, they behave like a solid. Since my pushrods have never fallen out, and the minor ticking never changes after a blast; I have to assume that the lifters have never been squishified. The proof, I think, is in the 93 mph Eighth-mile, with that smallish 230 cam