I own a few of the chrome-nose FDs' along with some of the newer ones. As someone mentioned before, the CN were the first of the FD lenses with production starting in late 1970 and lasting until 1973. Generally, along with the coating differences, the CN seem to be more robust than later FD lenses. They are definitely heavier. I prefer the chrome-nose variety to later FD lenses mainly because of this robust, cost-be-damned, build quality. Others like the newer FD lenses because of their smaller size and weight. Personal choice as to what suits you best.
Jim Bielecki