Re: Semi-Auto 308 WIN
The Armalite and the DPMS LR-308 type rifles both offer advantages and disadvantages. Both are very capable platforms and either will offer you what you are looking for. What specs are you looking for other than "light" "battle rifle"?
The 16" barreled AR-10T rifles were excellent, accurate (sub-MOA capable), and dependable rifles. However, they were not exactly "lightweight" by most people's definitions. The advantage of the heavy, match grade SS barrel and free-float tube is a big advantage for accuracy purposes, but those options increase weight. For comparison sake...the 10T 16" with proper ammo and shooter is capable of 3/4 MOA accuracy while the 16" AR-10 standard carbines were only guaranteed for 1.5MOA. So you are talking about roughly twice the accuracy potential.
FWIW, Armalite no longer offers the 16" 10T, so if you are looking for one, you are going to have to find one that is NOS, used, or have a an upper made to your specs with a 16" T barrel.