A Larue mount, or similar, provides the proper height for the scope, and clearance for an iron sight like the one on mine. Also, allows for easier access to the charging handle, and proper eye relief.
Sometimes higher power scopes in standard rings will not fit on the top rail. The larue mount solves this problem by being one piece.
Just depends on the scope though. The other advantage of the Larue mount is the ability to be quick detach. I can remove the mount and scope combo, run the gun with iron sights, re-attach the scope in the same position on the rail, and the scope will keep it's zero. (trust me it works).
I run a 50 yard zero, which makes me scope just about dead on at 200 yards. I have tested the Larue mount many times, and it will hold zero, even out to range. (Have you figured out i'm a Larue fanboy yet??
See this linK: Larue's description of the advantages of their mount, but applies to similar style mounts as well.