I've had 8 and 8 1/2's and haven't seen a velocity advantage with the slower. My go to load was H-4831-SC at 3060 with the 142's in 30" tubes. Primer pockets still holding after a dozen firings. 140 VLD's seem to prefer 3 grains less at 2950 or so. All moly, all hard in the lands.
I sure have and I will go so far as to say I see even more improvement in 1-9 twist but some barrels don't really stabilize the bullets good enough to use them at lower elevations.
I can shoot great groups at the range in prescott, AZ (5500') but they don't shoot worth a hoot at the range in Mesa (1400') I guess they are on the ragged edge of stability.
I competition, we used to find the best accuracy at around 2900 fps. When I switched to 8.5" twist I could go as fast at 2970 with good results (28" barrel) never shot a 9" twist in a match but with a shorter barrel, I can push them just about 25 fps faster.
I prefer 130s for the vast majority of my shooting, I feel like the added velocity pays off at the 600 and under shots that I mostly take. I am a big fan of the 130 Norma Diamond Line.
