When I first got online and discovered this gun forum thing, asking about a .50 ACP was the second post I put up. The concept gets renewed every so often, with mixed reviews. While I agree with all of your reasoning, Snowman, most people seem to regard it as just too much, which makes little sense to me. I would think that a 300-ish grain bullet loafing along at 800 or so FPS would be the greatest thing since sliced bread, and double-stack 1911 mags and frames would easily lend themselves to accomodating the extra width.
Alas, I would think the underwhelming positive resonse to the idea indicates commercial non-viability.
However, over on TFL there was a guy by the handle of Alaska Roy who was building up a custom project based on a Glock 20 and shortened .50 AE brass. At last posting, he'd just ordered barrels from Bar-Sto, but he never came back to tell us about how the project finished up.
Additionally, I have read about a similar project being worked out in a gunrag, but I can't remember what the platform was. I do remember it was going to use cut-down .284 Win cases.
There was a blurb about the SHOT show a couple years back where-in someone was debuting a .50-caliber round in a 1911 platform, but it was a magnum-class round with 260+ grain bullets moving out at some 1250 FPS, which is too hot for SD. .50 P-something, it was called. Padua? Palau? Something similar to that. Haven't heard a peep about it since.
I need a couple of machine tools. I don't feel like paying mucho cash to a 'smith to create one of these for me, I'd rather build it myself. Just as soon as I win the lottery, promise!