Here is one other issue not yet mentioned; it took a long time for AR-15/M-4 rifles to overcome the "jamming" issues we were raised on from the Vietnam era. Now we know that the AR rifle is a very, very reliable gun in most styles, but for many, many years it was assumed not to be. Just like with the Army, reputation bias and rumor kept a lot of law enforcement gun buyers away from the AR for a long time.
PCC Colt AR's had an even worse rep, as they jammed a LOT compared to the Mp5 and Uzi series of 9mm pistol caliber guns. The all steel angles of the UZI just wasn't all that user-friendly for the average Joe/Jane homeowner, and the Colt AR PCC and Mp5 were very expensive compared to today's PCC's, so those guns weren't even brought up in a HD scenario.
For duty use, until the last 8-10 years or so it seemed like every agency SWAT team deployed Mp5's, while very few had Colt AR 9mm's and fewer yet the UZI. Now even the use of the Mp5 is fading fast, it seems everyone is using the 5.56 M-4 style carbine for all SWAT and patrol type duties. (I personally carried Mp5 and Mp5k's on details for just about 10 years, and for several years before that an Mp5 often rode in the trunk of patrol cars. I LOVE the guns, but recognize their limitations in a firefight situation.) In my own HD situation, I do not foresee the types of engagements that I trained for when working SWAT/SRT, etc.
PC AR's have finally gotten to the point where they're much more reliable than they were, they often have last-round bolt hold open and most use common pistol mags rather than converted UZI or Colt factory mags that cost a lot and were often balky in the AR PCC.
And yes, the rifle-style PCC, beginning with the older Marlin and original Ruger PCC's to today's Ruger PC9/PC40, can be bought in states with the AR ban because they don't look "evil." I fully recommend them for most applications, especially here where the AR is now taboo, since they're accurate, easy to operate and best of all are fun so people like to go shoot or practice with them.
I have almost as much faith in my PC9 with Glock mags loaded with good SD rounds as I do in my BCM 5.56 for a HD situation in the home. (If I was on a farm/ranch or caught outside the home I'd rather have the BCM because it has more reach if needed.) They are a great HD option, and in the hands of a competent and confident home defender are very effective tools!
Stay safe.