The valve train is a major source of engine friction which takes HP to overcome. Reducing HP requirements in this area can only be good. Lightweight rocker arms also reduce valve train weight to help prevent high speed valve float. I'd be interested to see what they have.
However, a big "plus" with the factory rocker is the "built-in" safety margin. If a valve happens to kiss a piston in an over-rev situation, the rocker arm will break and absorb most of the valve train trauma since it is made of cast iron (cast steel?). Most aftermarket rockers are made from billet or forged steel or aluminum which are so strong they won't break - so something else does. But then again, with a lightweight valve train, an over-rev, kiss-of-death may not happen as readily.
Keep us up-to-date. Thanks.
Sherwood Lee
http://members.rennlist.org/911pcars