A buddy of mine has a DPMS LR-308B with the 18" Bull Barrel. That would not be my first choice for a Hunting Rifle as it is just as heavy as my .223 DPMS Panther Bull 20 AR-15.
At any rate we have shot several different brands & types of ammo and a couple handloads through my buddies DPMS LR-308B. In addition we have also chronographed some of the ammo through both my 20" Remington Model 700 .308 and his 18" DPMS LR-308B. Generally there was 13 FPS difference in velocity between his 18" DPMS LR-308B and my 20" Remington Model 700 with the same ammo from the same box. I don't know of anyone that can shoot good enough to tell the difference 13 FPS is going to make in trajectory or wind drift.
To take the barrel length thing further I have hunted with Speciality Pistols for several years. Typically these had 14" to 15" Barrels. While I have not used a Speciality Pistol in .308 Winchester I have used a host of other cartridges to include the .243 Winchester, 7mm-08 Remington and .284 Winchester to name a few. All of these short barrel Speciality Pistols are capable of accuracy that would make a lot of riflemen sit up and take notice when shot from a bench. This is all based around barrel harmonics with a shorter, stiffer barrel being more stable than a longer, skinnier barrel.
With that said I have been contemplating a DPMS LR-308. I have been looking over the DPMS web site comparing lengths & weights of the various versions. In the end I am thinking if I do purchase a DPMS LR-308 it will be the DPMS LR-308T with the 16" Barrel and Aluminum Free Float Tube with a Fixed A2 Stock.
The modifications I would do to start with is a JP Enterprises Adjustable Trigger and Remove the Flash Hider and replace it with a knurled thread protector. Other than that finding the right ammo would be all that I would think would be required to make a dandy hunting rifle.