I find 2,700fps to be the cutoff from push to smack. All the moderate old cartridges with reputations for being kind, that still throw respectable bullet weights (a .243 may be quick, and soft, but you're throwing out pencil lead) are at or under this velocity typically; .303, 7x57, 6.5x55, .30-30, .375 H&H, .450-400 etc.
The faster you go, the sharper it gets, my .375 H&H can push certain bullets magnum fast and it really starts to bite. With 270gr, 300gr, and 350gr standard loads it's downright friendly to shoot (it's all relative, still much more than my .300 Win Mag Express rifle but WELL below the discomfort zone you find with even certain .338's).