First, let me say that being thoroughly confused by the term for quite a while, I think Sig should have called it the "thin trigger". Less confusion with the "short trigger action" on the P220 Elite and the P229 SE.
The "short trigger" is a thinned-down regular trigger that is starting to make its appearance on newer models. What Sig doesn't say is that it's a perfect replacement on their older models, too. For me, at least, it brings nice, if not earth-shaking, benefits. Here's both the P220 Elite and last year's P229, both with the new-style trigger on them. In the corner is the "old" and "new" trigger for comparison.
The "short" trigger is just the old one thinned out in the middle of the trigger bow. That brings the surface closer to your hand. Your "reach" may be shorter, but the trigger is still the same length. If you wanted a longer reach for the trigger, you could put the older one in on any of the new models.
Since this picture was taken, both Sigs, and the Kimber Covert Ultra now have Trijicon night sights. I have a major rant against Meprolight, which I will save for some other day. Let me just say, save your money for Trijicon, and run away from Meprolight.
The major ergonomic difference between the two handguns involves the treatment of the rear of the grip. The new Sigs, with a redesigned hammer strut and hammer spring housing, allow the rear of the grips to be brought more forward for a more compact grip, if you like that kind of thing like I do.
The P229 has a more rounded, droopy "butt" than the P220. It still feels great to me, except in comparison to the new-style P220. I'm sure there will be replacement parts out soon to pull off a conversion, but it probably won't be cheap. And since I have my .40S&W conversion kit, there's not much more in store for the P229 except a .357Sig barrel.
Of course, the other difference in feel is that the P229 has a chubbier frame designed for a double-column magazine, while the P220 is slimmer, despite handling a longer, fatter cartridge. That's due to the fact that the P220 still uses a single-stack low-cap magazine. Here's the main difference in widths, which shows the wider, stubbier grip of the P229.
As far as M1911 short triggers go, the old warhorse has a short trigger now, an alternate brand I bought while checking out various types. I need another Wilson Combat short trigger for the Kimber SIS Pro, to match the Ultra. I also would like to find a black short trigger with three holes to match what's on the Covert Ultra. That one may be harder to find unless I do more searching.
Another major item in the pipeline is a Bar-Sto .357Sig barrel for the P229. It seems that Sig is slow filling orders for lots of parts. Still, even though I'll probably only shoot it once, I want to fire that .357Sig just to see how loud and obnoxious it is, and get back at some of the other people on the range. :)
Finally, this last trip to the range showed me that I was spending more time looking for the laser dot on the Covert, and adjusting my grip to keep it turned on, than actually using the iron sights. I turned off the laser, and shot much better. This is getting me to think about removing the laser grips completely, and going with something else. I just wish I could find some plain plastic grips with the same Marine desert camo pattern on them. I've gotten used to that look.
That, however, is the least of my problems.