Can't comment on your AR swap-out options but I can on the 15-22.
Firstly, to clear up a point that quite a few people stumbled over, there was a recent safety
alert but there was
not a recall.
S&W asked everyone to perform a quick & simple check on their own rifles. It wasn't a biggie, so don't worry about it. If your going to buy new, your rifle should have been checked and if not, there's plenty of information about it on this forum.
I've had several rimfires in my time (Anschutz, Vickers, CZ, BSA) and, just like many thousands of other owners, none have put a smile on my face like the 15-22


.
It's a great little fun shooter that's very accurate, reliable, easy to strip & clean and is simple to use.
Yes, they can sometimes have their little faults, but the same can be said for just about every other make of rifle out there. Even the magabuck models aren't perfect so try not to get hung up on the occasional guy that's trying to make major issues out of trivial matters.
If you get the opportunity to try one out I can guarantee you'll enjoy it but be warned, an itch will set in very quickly that just has to be scratched


so enjoy.
Iain
PS. yes, the barrel is threaded