I absolutely love my 15-22. Ive put well over 2000 rounds through it, and had maybe one misfire, and that was the round's fault. I use Remington Gold 525 bulk, and it loves it. I love the weight--it is about 5-6lbs, and just feels natural. My old ISC M4 weighed more than it. It isn't the cheapest option out there, but is by far one of the best quality dedicated .22lr armalite rifles. Originally I was looking for a SIG 522 or GSG5 MP5, but these both were in the upper $500's. I found my 1522 used at a local store for $400.
The upper and lower are polymer, as are the rails. Mine does not have the threaded barrel or birdcage flashider, but did come with a flip up front sight post, and a milspec short sight at the rear. I have considered getting a MBUS or other rear sight, but wanted to see what I was going for first. The receiver extension tube (fake buffer tube) is milspec standard and is also polymer. The trigger is very crisp and predictable, leading to a very accurate rifle. The only wiggle is in the LE stock, as the receivers fit perfectly together, and I am looking into getting a MOE stock or CTR. It is not picky about ammo (unlike my .22 pistol), and does not care to get a little dirty or go a little while without a cleaning. It breaks down exactly like an AR15, and the upper comes right off. However, the lower cannot accept a .223/5.56 upper. I really love this gun, and feel that it is every bit worth it. For me, buying it used and with some ammo, I got out the door for $445 ish.
I currently have a UTG 4x20 mildot scope with 5.56 drop compensator that I mount on a AR15 carry handle. It adds quite a bit of weight to the gun and makes it top heavy. I like the scope, but the reason I want to replace it is the paralaxing....It is ONLY designed to be on a AR carry handle... and when using the flat top mount, has to be in the same spot due to the SHORT SHORT distance for it to focus with your eye. I personally like irons, but enjoy what optics can do for you. However, I will never run a gun with only optics and no BUIS.
Ive been looking at Aimpoint style sighs or EOtech sights due to the AR15 design--I cant bring myself to use a simple dot sight. However, I will NOT actually buy a $400+ sight for a $400 rifle. You addressed my two main concerns on the nose: Co-witnessing (I dont mind 1/3 or true cowitnessing, either works) and losing zero due to well, stuff cheap construction.
I was looking at sights similar to what you posted, the aimpoint clone, and
http://www.amazon.com/Style-Military-Ta ... 064&sr=1-9I'm also curious if the Magpul PTS CTR and MOE would work, considering it was a .22. I am not trying to cheap out and cut corners, but with AR type rifles it is TOO easy to dump half or as much as the gun cost into accessories.