First off, if you are truly serious about running a 1911, it needs to be a full sized 5" gun in .45 ACP. There certainly are any number of examples of Commander and other compact 1911s that work or can be made to work just fine, and for CCW use they can be a viable option for some users. However, take a look at the history of unit issue service 1911s – LAPD SWAT, USSOCOM, USMC Det-1, USMC MEUSOC, FBI HRT, FBI SWAT, and let’s not forget over 95 years with all the branches of the U.S. military - and you won't find ANY major units that use anything other than the original full sized gun. Why? After you field 50 or 350 guns at once and run thousands or even tens of thousands of rounds through them during training cycles, you'll figure it out. By virtue of their design, the shorter format 1911s reduce the window of functional opportunity for the magazine and slide to work together to feed, chamber, extract, and eject. This is an incontrovertible fact of life. Proper weapon setup, spring rates, and magazine maintenance are critical in running the shorter guns. Keeping after a few 1911s as a single hobbyist or aficionado is different than running a bunch of guns for a large unit. Remember that weapon down time equates to lost training and operational time. You want to minimize your maintenance issues, not increase them. Lastly, a full sized 1911 is very arguably a more efficient shooting and ballistic delivery platform than a smaller sized variant for the majority of users.
Over the years, I've owned a number of 1911's. The only ones I've ever had any issues with have been guns with less than Commander length barrels or had a name other than Colt on the slide. My Colt Commanders worked just like my Colt Government models, flawlessly. I've shot thousands and thousands of rounds out of the Commanders without any problems.There are lots of people who own and shoot Commander and even shorter length 1911's "successfully" but we should discount those who claim they've shot a 1000 rounds without any problems. Statistically 5" 1911 tend to be better in the long run.
Over the years, I've owned a number of 1911's. The only ones I've ever had any issues with have been guns with less than Commander length barrels or had a name other than Colt on the slide. My Colt Commanders worked just like my Colt Government models, flawlessly. I've shot thousands and thousands of rounds out of the Commanders without any problems.
Also looking at what FBI, USMC, etc prefer IMHO is not really that usfull in that they are not trying to conceal the weapon but are generally wearing it either on a LBE vest or in a thigh holster.
How much easier is it really to conceal a Commander sized 1911 than a full size one?
I think a lot, due to the weight of the full size, and, I have one. You need a real heavy belt, like Dillon sells, to hang the holster on. The alloy Commander frames make a big difference.
I'm a big guy (6'4", 275lbs.).
Subquestion -
I've heard that reliability in the compact 1911's can be sketchy. Is there any truth to this?