amprecon echoes my sentiments exactly. I had the M1A on my "to buy" list for eons, and finally took it off. I could never justify the price for a .308 gun that basically I could only hit at 150 yards with irons. Once you decide you want to scope a .308 platform, there are better options out there. I also realized that fast semi-auto plinking is best on cheaper cartridges, like .223 or 7.62x39. What's the point of blowing through a box of .308 in 60 seconds, really? This is all my personal opinion of course.
My only real reason for wanting an M1A was the looks and history, not practicality. If I had infinite money to spend, I'd probably get a PWS MK216 over the M1A anyway, and even that is of somewhat dubious use.
So yah, AR15 type platform for .223...sure. AK47, SKS or Vz.58 for 7.62x39 and boatloads of Brown Bear ammo...yep. A .308 battle rifle? Ehh....I'll take a bolt action myself and make each round count.
(Of course, if I was given an M1A, I wouldn't turn it down!)