Pistol Pete,
I purchased an AO 1911A1 pistol on 2 Jan. To date, I have not had the opportunity to take it to the range (or my Beretta carbine

) due to cirmcumstances beyond my control.
Having been issued a Remington Rand .45 that was four years older than me during my tour with the 2nd Infantry Division in Korea, and after examining plenty of GI 1911A1's over the years, I would say that the AO as made by Kahr is much better fitted, and the Mass model does have the Series 80 firing pin safety (I know purists get bent out of shape over that). I used to own a Colt Series 70 and still own a Mk IV Series 80 which has some customization.
I don't think that it would be fair to compare the AO with a 2,000 dollar race gun, or even one of the more expensive S&W models. But for value, I think it is hard to beat. Perhaps my opinion will change when I finally get to fire the pistol...the proof is in the pudding, so to speak.
As for MIM parts, I know of no major manufacturer who doesn't use them in the firearms industry. Now I can't speak for the smaller custom shops like Ed Brown and Les Baer. I have heard the MIM arguments before, but I have had forged parts break including firing pins.
At one time or another I have owned or was issued (Baretta M9) all of the major brands of service grade autos except Glock, and my two favorite auto pistols are the Browning Hi-Power and believe it or not the old S&W M39. Despite an atrocious double action trigger pull, it fits my hand like a glove, and has a certain shootability and pointability about it that Smith was never able to duplicate in the 3rd Gen Guns and the Tactical Series.
If the 1911 works best for you, that is great. To me it is the standard by which all other service grade autos are judged. I have small hands and I don't like the flat mainspring housing, but today one isn't cool unless one uses that format. Full length guiderods are another thing.
Like the B52 Bomber, and a Steinway Concert Grand Piano, or a C-130 the M1911 is a refined product of a very mature design.
I do have reservations about using any single action auto as a civilian personal defense weapon. That reflects the teaching and writing of Mas Ayoob. Perhaps I am being overly cautious and certainly there are enough people who disagree. For that reason I will use a double action auto or revolver as a carry gun, most of the time. Were I to find myself transported magically to Afghanistan there would probably be both a Browning Hi Power and a 1911A1 riding in my cargo pockets. They would both be fairly stock, too.
Good shooting with whatever is your favorite gun, to all and espeically you Pistol Pete. It's always good to meet a man who knows what he likes and sticks to it.
Mark