The '67-'72 factory intakes are very good. It was Pontiac, not "GM" that developed them. With significant port work, they become VERY good.
Performer IS lighter. It performs as well up to about 4,500 RPM, where the factory Q-Jet intake is a bit better up to 5,500.
The first EGR intakes ('73-'75) had a HUGE EGR provision cast into them, hanging underneath. They easily weigh 30-40 lbs. more than the others. The later EGR intakes (with the "flat" on the secondary openings) flow better than the earlier EGR units and are significantly lighter. Still a tad heavier than a non-EGR unit.
Jim Hand's tests were all done on HIS combination, which may or may not apply to yours. We've read the tests. We were there when Cliff tested Hurricane ("Tomahawk") and LOST speed and ET. Unfortunately, assumptions were made, "lumping" ALL the open-plenum intakes together.
We could "debate" this subject forever. We've (CVMS) found the Torker and Torker II to be FAR better performers than any of the other "open" intakes, and in most larger-displacement applications, better than ANY others. My point is, there are NO "absolutes". Each one has its "place", though some ARE better than others. Calling the iron intake Cliff and Jim use "stock" is not really fair, as both have MANY hours of porting in them.
Suffice it to say, there are several to choose from. Your particular combination is what should determine your choice.
Jim