Actually, the Marine Corp's program is very effective, in what it is intended for-killing your opponent. Most martial arts don't teach how to kill, they teach how to defend. Very big difference. I have watched Marines train, as well as Army Airbone Rangers, and their systems are very effective, however bare of tradition, fancy names for everything, et cetera it may be.
As for ho well it would fare against any other martial art, i have no idea. But given the choice, i would prefer to be attacked by a martial artist, since they are trained to defend themselve, not kill you.