Interesting to note that they put a shotgun butt stock and recoil pad on this one, so I guess they're serious.
One of the things to keep in mind is that Uberti Arms, and all other Italian makers, are required by law to have their products proofed by the Italian government in state owned proof houses. The proof loads used in Italian proof houses exceed those used in this country. If Uberti marks their new 73 for 44 mag, then it is proofed and meets SAAMI standards for the 44 mag or they would not be allowed to export it - their rules, not ours.
One of the improvements necessary to make this possible, is the strengthen design of the bolt and firing pin assembly, which now uses the "key" to retain the firing pin extension, rather than the wimpy cross pin in the early design, which could, on rare occasions, shear. The "Key" is also used in the 76 Uberti. Much stronger set up and more like the original Winchester.
I have never seen pics of any blown 73 or 76 that resulted in collapsed links - only burst breeches and barrels.
My only question is why? I don't like the 44 mag in any light weight carbine!
Now as to the question of why we keep smokeless loads for the 76 on the mild side of things, it is primarily because we are on untested ground, and must proceed slowly and cautiously until more data is confirmed, either by field trial or in a lab.