I have now owned both...a postban Bushy and now a preban Colt. Both had/have chrome lined and free-float barrels. I SWEAR my Bushy was more accurate. I recently shot the Bush again when I went shooting with the guy I sold it to and shot a much tighter group. Both rifles were bench rested, same ammo. Yes, I know having a flash hider changes the barrel's "harmonics", but...
So, get the Bushmaster and apply your saved change to ammo or extra mags! The only way I would buy a Colt is if it was a preban...because by that time (money) it is as much an investment as it is a weapon.
P.S. There was a recent blurb about Colt Vs. Bushmaster accuracy in "Gun and Weapons for Military and LE". The article was actually a review of a new suppressor, but you will get the idea.