I spent upwards of an hour the last two days with google looking around at this. This topic has come up several times over the last 3 years and generated much speculation, but I can't find anyone who's actually tried to beat on one. Most likely, owners heed the consensus opinion: The gun will shoot it self loose sooner rather than later--which is what I'd expect, too.
At first thought, the .44 Mag in a '73 seemed pointless. On second thought, I can see some advantages for the reloader. The straight wall case is readily available, sturdy, and works nicely with carbide dies. Loading to 20,000 psi gives plenty of performance for jacketed bullets, and the 36,000 proof rating means you have plenty of room for error in your reloads. I still don't want one, but I'm more sympathetic to the gun.
As a variation on the theme, the .44 Mag '73 is interesting, but I'd have been more interested in a .44-40 on an anodized aluminum frame. That would get the weight well down and make for a nice handling gun (by my likes).