My car has had a solid roller in it since 2003. I did a top-end on it a few years back and the solid roller lifters (comp) were fine.

Mechanical rollers on the street all depend on the valve spring rates. My cam comes out to: .552" with a 1.5 ratio rocker and about .250 @ 50 degrees for duration. Overlap is 111 or 112 degrees. This cam would be considered a "street" roller.

I have had engine builders tell me that mechanical roller motors simply make more power on their dyno's.