Solid rollers on a hydraulic roller cam?

My oldest son Brian has run his a few years 3 or 4. Last year he checked them twice. He is due to check them again. This is in his 4 door valiant, which is his only car.
He has a pretty mild cam though , [email protected] and 540 lift.

I want to add to what I said above, that Brian has 273 rockers. We did Yellow Rose's oiling mods to the rocker shafts, so the cups get plenty of oil. I think that is what keeps the lash from going .