The 1911 model IIRC originally came from the factory with a lose fit to insure reliable function.
The tightly fitted and extremely accurate 1911's are a fairly recent developement. Many call em Race guns. Most are very expensive to create or purchase.
Kimber 1911's are basically Race guns right out of the box at a lower price.
Have known a few people that purchased Kimbers and NONE have had any problems with em.
The STI, IMHO, is a great firearm but NOT my cup of tea. The wider grip, to accomadate the extra ammo, is too big for my hand.
If you can afford the Kimber IMHO buy it you won't be disappointed.
A brief note: The commander and officer models tend to put the ejected cartridges straight back, and up, and onto your head where the standard 5 inch barrel jobs tend to eject to your right, up, and rear.
Another brief note: Maintain a firm wrist and grip as some 1911 will stove pipe or have ejection problems without a firm base for recoil to operate against.
A finale brief note: Recoil springs! Beware a too weak or too strong recoil spring will creat problems. Many 1911 come from the factory with a fairly stiff recoil spring on purpose. If you elect to replace this spring with a weaker or heavier recoil spring then consider putting in some sort of recoil buffer device to avoid frame damage!
Love the 44 mags, and the 357, but fav is the 1911 in .45 acp.
The 10mm is a very potent round and there have been complaints of poor accuracy and excessive recoil with this round. This resulted in the birth of the .40 cal. round.
Many report both excellent results and reliabilty with the Chip McCormick mags. And the price is reasonable.