$500 to $2000 is quite a spread! I have a 2007 M14S, I am one of the lucky ones I will admit, changed Op rod guide and spring, shimmed the gas cylinder and replaced the ugly mystery wood stock. I put on a M14.CA scope mount as I can't see crap anymore with regular sights! (the Norinco sight was .... cluncky and not even a properly drilled aperture. It shoots anywhere from under an inch very seldom to 2.5 inches quite often (scoped) depending on the ammo and the alignment of the stars that day. Over 2000 rounds with out a malfunction though. I do like this rifle!
I also have an M1A loaded that I bought expecting a much better rifle than the Norinco. I was right when it comes to accuracy, the medium weight barrel leaves the Norinco in the dust, .5, .9, 1.4 inch groups are very common but so are 2 inch groups a times..... I'm a lousy shot some days!
The M1A has about 1000 rounds through it and I have had some trigger issues and have recently noticed that the Op rod is hitting the reciever where it curves around the front of the reciever (out side of the stock, not on the face of the receiver where it is supposed to hit) at it's most rearward travel which will likely compromise the longevity of the Op rod as it hits on the curved area which will likely cause it to break there eventually. I emailed SA last week to see about warranty issues in Canada and will see how this goes. My point is.... Norinco if you get a good one great deal, SA if you get a good one great deal. I will wait to see how SA deals with Canadian warranty issues before I decide!
Almost forgot, both the Norinco and the SA needed to have the gas cylinder shimmed, replace stock, and replace the Op rod spring guide so no clear winner on the " tweaking" requirements.
Edit!! forgot to clarify.... I am indeed one of the lucky ones. I understand some of the Norincos have significant issues, if I had one of those this post would read quite differently and would likely be talking about how the reciever was being used for a new build! Of course I am thinking about a new barrel to improve accuracy and Tree line M14 has all the other parts I don't need but want to upgrade...crap, likely will end up costing as much as my SA anyway.
Rodney