OK -a lot to cover here, so here I go. As always , YMMV.
A rimfire AR is no more or less accurate than any other blowback rimfire with the sights mounted on the barrel.
My CMMG 16" Sierra AR-15 .22LR upper has proven to be more accurate than my experience than a stock Ruger .22LR, Remington 552, Marlin 60, or my brother's old Winchester Model 74. Of course, none of these rifles are take-downs.
As for reliability, they work the same way. I suppose you can argue that the oversized magwell relative to need could be a problem for the AR. Also, some of the ARs have extraction and ejection compromises (e.g. some count on case pressure for extraction, some use the firing pin for ejection) and the AR provides a well for spent brass to get trapped in, all of which reduce reliability at least in theory.
There are a wide variety of .22LR AR-15 options out there, and there is obviously a difference in quality. One would expect a pricy Nordic components or Spikes .22LR AR, or a mid-range priced CMMG, to perform better than the lower end offerings from Chiappa/ATI. Then you have the cheap "look-alikes" like that Mossberg Plinkster in a plastic AR-looking shell.
Again, I can only speak to my experience with a CMMG. All failures I've had have been ammo-related, which is par for the course with rimfires. I've found the reliability to be equal to a Ruger 10/22, and considerably better than a Remington 552. I'm not sure of the "well" you speak of to trap spent brass. My CMMG has a 9mm-style brass deflector and a solid charging handle. There is nowhere for spent brass to go but out of the gun.
Ergos of an AR .22 aren't better than a non-AR. There isn't enough recoil for bore line to make any difference. The charging handle is designed for a completely different cartridge and doesn't map well to the rim fire. Pistol grip ergos are different but not conclusively "better".
All personal opinion. I definitely prefer the rotating selector of an AR (to a push button safety as found on most semi-auto rimfires), the mag release, and the options for adjustable stocks and pistol grips. To each his own.
Six pounds is arguably too heavy for a 3000+ fps .22, which is why you can buy carbon fiber ARs. For an 1100fps .22 it is at least 2 pounds too heavy. The point of a take down rim fire is to have something small, light, and easy to bring along. Two pounds would be nice.
I'm not going to necessarily disagree with you here. For a pure "survival" rifle that you are traveling with and will only be shooting as a last resort, the lighter the better. For anything that you will be shooting for sport, I'll take a more useful gun every time. Again, no one usually thinks of an AR-15 as a "take-down gun" but it is an option I'm just pointing out.
