From the information I've gathered, the 16" barrel automatically puts you in match rifle class, and your 16" won't compete. I have found out that now the detachable carry handle is legal, but does not have enough elevation for 600 yards, so you have to adjust the front sight, which may not be a close enough tolerance, not to add windage changes to the overall picture. Advice on the high power forums is to an A2 style fixed sight upper, with a 20" barrel. Don't feel bad, I just built a 20" Shilen barrel upper with a detachable carry handle, barrel free floated under the handguards. LOL, I think I will just shoot it and see what happens.
As to how much you give up, 200 fps, and then it depends on the bullet weight, ballistic coefficient and velocity versus your barrel twist rate. 16" barrels can shoot very well, but if you want to shoot high power, the extra velocity and sight radius are a plus.