In favor of the .308, when you buy the Federal Hi-Energy rounds with the 180 grain bullet, you get virtually indentical ballistics with the standard 30-06 round and 180 grain bullet. So again, the .308 is much more versatile on the high end than the 7-08, particularly if you do not hand load..
I have used the .308 on deer, with factory loaded 150 grain bullets, for many years. I have 13 one shot kills, and 2 two shot kills. No missed or wounded. It is a wonderfully efficient and accurate round.
But, if I were going to buy a carbine, with a 20 inch barrel, I might just go for the 7mm 08.
Big Paulie