Recoil and how we experience individually is a funny thing. I think the recoil-induced pain and discomfort are as much a function of a handgun's design (ergonomics, weight, bore axis, grip design, etc.) as they are a function of caliber and ammunition choice. Then you also have the factors of the individual shooter: size, strength, ability, and experience.
I guess what I'm saying is, my limit is very handgun specific. I'm a pretty big guy (6'5", 225-230) and I work out with weights a good bit (including a number of hand-strength exercises). I've been shooting guns all my life.
All that being said, I cannot comfortably shoot an alloy j-frame in .38 special. It just plain hurts, and I suspect it gives me a flinch. Forget about the 10 oz .357's I owned.
OTOH, I can comfortably shoot a Ruger Redhawk in .44 magnum. It fits my hand well, and its very pleasant to shoot, actually. Ditto for the Ruger Blackhawk in .357 w/full-house loads. Easy as pie, can shoot it all day. I can shoot both guns much more accurately than most other handguns.
A SIG Pro in .357 SIG? Painful and uncontrolable. Twisting torque and muzzle flip.
.40 Cal Glock 27? No pain, no torque, just can't shoot it well at all. Same gun in 9mm? No problem, I put them all where I aim them.
1911's and SIG p220? Like shooting a laser beam. Recoil is not an issue.
I guess what I'm saying is, there's alot of factors in a recoil "limit". For me, it seems to be a matter of how the gun fits my hand, and how much the gun weighs, as opposed to any other factors.
-David