You know, I've read articles where a fellow (famous older gun guy....darn if I can remember his name right now) took an -06 and cut it down 1" at a time and crony-ed the same load from the gun after he chopped that inch off. I think when he got to 18" of barrel, that was the "magic" point where velocity began to drop significantly.
Then I've read articles where some short barrels will shoot the same load at higher velocities than long barrels. (Same caliber of gun). The reason has to do with chamber dimensions and throat length. I don't know if the explanations are "spot on" but the crony didn't lie.
IMHO, I think it comes down to what your going to hunt (if your going to use this for hunting....and I think that's the ultimate purpose). If 4" of barrel is going to drop your velocity by 200fps that's a consideration. But then, that's only a consideration if your shooting at game "on the outer reaches" of that caliber. So, if your shooting a 165 grain .308 and it's more likely that your going to shoot at game 400 yards away, then you probably want that extra 200fps velocity. But, if your most likely going to be shooting a maximum yardage of 200 yards, then that 200fps velocity doesn't mean so much.
Now, the shorter barrel is looking better since it's lighter, easier to maneuver in brush, and quicker to "bring to the shoulder."
And heck.....the deer isn't going to know if it was hit by the 165 grain bullet at 2700fps or 2500fps. It's just going to do a flip and drop like a sack of bricks.
Dave