For race cars I think smaller motors benefit more from a SR in that a big motor can take more seat to seat duration down low and still be responsive "enough" below the torque peak while at the same time can get adequate .050-up cylinder filling for the heads/peak power RPM from the flat tappet. A comparable flat tappet generally needs more (beyond) peak lift to be comparable so you can get the same effective peak lift duration, and in some cases you can be limited by the steepness of the ramp you can put on a flat tappet. That was (in the early days) a Big part of the reason mushroom tappets were developed.

With a smaller motor it can benefit more from a tighter seat to seat while using the roller lobe to "catch up" at the higher lifts, a smaller motor generally has a narrower powerband to begin with so anything you can do to broaden the powerband window tends to make it more consistent.

my .02 FWIW...interesting thread though...I'm enjoying it