No selection for 'ammo'.
The 1911 has it foibles, many of which have to do with design. It's a 100 year old gun, and materials, engineering and manufacturing technologies have made an advance or two. The fact that the 1911 still makes the short list of serious combat pistols says a lot, and the designs that dominate today all own a debt of gratitude to the old slab side. The best designs correct some of the 1911's peccadilloes.
My take is that if you build a milspec gun and feed it ball, it has very little in the way of problems. It was designed to be reliable with ball ammo as it's basic criteria. Now we try to make it shoot cloverleafs and feed wadcutters. That's probably asking a lot, and no one should be surprised if it needs some tweaking. Most modern autos were designed to function with HP ammo.
The weaknesses I see in the 1991 are the feed ramp - which require perfect geometry and a good finish if you want reliable feeding with ammo that's not GI spec ball. The Extractor, which must be properly tensions since it is both extractor and extractor spring all in one, and the barrel lockup system which is overly complex and difficult fit for both accuracy and reliability. The bushing system works fine, but is a bit of an annoyance.
Modern makers (some, anyway) have done a great job in maintaining the original design while getting it to work with ammo it was never designed for, and give levels of accuracy never specified in the original requirements.