Old Griz - Did you end up buying one or the other? or are you still thinking about it?
I vote for the M1A.  Have you handled either?  I would bet, that with a nomiker like "Old Griz", you would be best pleased with a heavy, solid weapon of steel and wood, rather than something made of aluminum and plastic that rattles and feels like a toy.  I know many swear by them, but after handling my brothers "black rifle" I was very unimpressed.  Besides, since you have a .223 already, a .308 makes sense.