I have 4 Kimber 1911 style pistols in my safe along with dozen other 1911 style pistols from Colt, SA and Norinco.
I purchased my first Kimber (Custom) in early 1999 followed by Target, TLE II and then Custom Carry II in late 2001 or early 2002. I shoot my pistols a lot and my Kimbers are among my favorite to shoot as they are also my carry pistols and occasionally my hunting pistol. My TLE II just passed 45k rounds few weeks ago and the Ultra Carry II is reaching 10k rounds with about 15k round with other 2 Kimbers.
While the TLE II is mildly customized other 3 are pretty much stock but I have had issues with some original Kimber parts.
On my Target model the adjustable rear sight broke 4 time within the first 2 years. None would last more than 3,000 rounds and one broke within 1,000 rounds. Kimber did replace the rear sight each time but it was obvious their adjustable sight were crap so I installed a Bomar Adjustable sight and I never had another problem. I never had any problem with their fixed sights and actually like them a lot.
I also had 3 slide stops break on me. One on the Custom, one on the Ultra Carry II and the TLE II. The one on the Ultra Carry broke early...within first few hundred rounds but others lasted longer...several thousand rounds. I always replaced the slide stop with Wilson part when they broke and never had any problem since. On the Target model I replaced it before it broke.
I had to replace the plunger tube on 3 pistols...twice on the TLE II. This is common issue among 1911 type pistols as this part is frequently steaked improperly. Even the Wilson plunger tube I had installed on the TLE II failed after about dozen years.
Finally, I had to replace the barrel link on my TLE II few years ago with a Wilson part. The original link was starting to get deformed but by then that pistol had fired over 35k rounds.
The thumb safety on the Target broke couple years ago and I replaced it with a Wilson part. Just to be safe, I replaced the thumb safety on other 3 with Wilson part at the same time.
I also replaced all the extractors (some more than once) as I found extractors on my Ultra Carry and Target had developed chipped edges after many. Also, Kimber extractors will not hold the correct tension on the rim after many years. I replaced all 4 with Wilson extractors.
These are parts that had broke (or worn out) on my pistols but I have witnessed some other parts break at matches. I've seen a sear on a Target II break into couple pieces causing an AD at a state match in 2004. When I got back from the match I ordered and replaced all 4 sears with Wilson part. I also saw a barrel bushing break at a match.
I have replaced all their nylon MSH with steel one as I didn't like the idea of non-steel part and all my 1911 pistols gets an aluminum short reach trigger installed immediately as they fit my hand better.