its not accuracy your giving up its velocity. all it means is your max range will be shorter by a few hundred yards and you get less thump on the target.
the concussion and muzzle blast from a short 16" barrel in 308 is rather unpleasent with a muzzlebrake. if you go 16 opt for a good flash hider your gonna need it.
my opinion: the whole point of a 308 is to hit the target harder at longer range than the 5.56. if your gonna go short might as well go 5.56 and get rid of the weight too. when i was going through the angst of deciding on short vs long barrel for my latest attempt at a 308 i might like, i went with a 24" barrel to get the most out of the cartridge.
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...