I've stated before that I really don't have a huge problem with MIM in most parts.  I don't like MIM hammers, slide stops, sears, and extractors.  Other than that, I don't care too much.

Many have posted their experiences with MIM breakages.  I noticed the other day that a Kimebr I dry fire a lot had a cracked firing pin stop.  Of course, it was cracked on the lower left at about the 7 o'clock portion of the FP hole, right in the corner.  This is where they crack 99% of the time.

I looked at all my other guns with MIM stops.  They are all cracked.  This particular Kimber has an Ed Brown FP stop for it, but I wanted to see how long it would go before I cracked it.  It's been about 2 years of moderate shooting and constant daily dry firing.  Also, I've done the same amount with a Colt and a Springfield.  The Springfield is cracked, the Colt is fine.

This is just an observation, and in no way a slam.  I'm going to keep on shooting the Springer with the cracked one to see how long it goes before cracking all the way through and failing.  I only posted this because I was thinking of all the 1911s I've owned, which is a lot, I've only cracked FP stops on Kimbers and Springfields.  

Recently replaced the MIM FP Stop on my Springfield GI.45 Repro for what I thought was no real reason other than a prejudice against Mim Parts. Bought a Colt stop from Brownells. It's served me while for several months with no sign of cracking or distorting.

After reading your post, it confirms I made the right decision for just a few bucks BEFORE it disabled my gun.

My first Springfield, the one they'll bury me with, took about 3 years to break the FP stop.  That was a lot of IPSC matches and practice, and LOTS of dry firing.  Plus, after the first year, I took the top 1/8" or so off so it would work with a set of Heinie slant pro sights.  

I'm not sure exactly when it originally cracked, but one day I took the slide apart to clean it and noticed a huge chip in it at 9:00.  The crack ran out from the center at 9:00 then turned and went to the edge at 11:00.  It was a MIM part and that's probably why it failed, but it also saw a lot of use.

Not a MIM fan, but I don't run home and replace every MIM part right away.