The composite tip mast was added around 1985 to prevent conducting electricity down to the boat if you hit any power lines, especially in the launch area. My mast is aluminum (1985 boat) and I was offered the "upgrade" free of charge but opted not to change it. I believe in racing the comptip is a requirement to be class legal. I don't race.
In addition to the comptip mast, the newer sails have no reef point. The metal cable portion of the older halyard was long to accomodate the second "slug" for reefing and if you had the sail up, that would negate the comptip.