I'm willing to bet that you're aware of some, if not all, of the things i'm going to mention, but I'll say them anyway,
yes they can handle the same loads.
the 50th has the flattop, SBH has protected ears
the 50th, not only has a round trigger guard, but also a much smaller grip frame than the SBH. It is a re-make of the xr3 grip frame which is smaller than what most New Model Blackhawks have on them. the grip frame is similar in size to a Colt SAA grip frame. Some folks have a little trouble holding onto these smaller grip frames (personally i don't, and I actually prefer them)
there's also a small difference with the lockwork. The 50th has a "reverse indexing pawl", what that means is that with the reloading gate open, the cylinder will click into alignment so a chamber is lined up with the loading gate (similar to old models). on the SBH, you just rotate it into alignment.......no big deal, but a difference. Oh the 50th will be equipped with a "lock" in the grip frame.
of course different hammers.
The following is purely my opinion.
I prefer the 50th to the square back SBH. It would be a toss up between a 50th and round trigger guard SBH. I haven't had a problem with any loads being too much with the smaller grip frame. Maybe i just don't shoot heavy enough loads. Who knows?
That 6.5" 50th balances real nice in my hand. I can't say the same about the 7.5" SBH.
in case you haven't, maybe check out CDNN, they have/had good prices on the 50th.