Very hard to do a true comparison between a points dist & HEI because of the different weights/centre plate configurations of the two different types of dists. This is going to affect the rpm range where the timing is advancing because of the centri curve in each dist.
Other considerations. With mag trigger dists, the flux wave generated by the trigger distorts & effectively retards the timing at higher rpms a few degrees. HEI should have been advanced slightly to counter this.
Plug gap. I assume that all testing was done with the same plug gap to reduce variables. Did not see plug gap mentioned, but probably 035 or less because of the points & high rpm used. A test by A.G. Bell in his book showed a 6 hp increase @ 3500rpm by going from a 035 gap to 045, no other changes. Given that HEI can easily handle a 045 plug gap, I think it was an apples-to-oranges test.
Testing done by D. Vizard in his A-series engine book showed electronic ign made more power every time. These are small engines, power went from 57 hp to 60 switching from points to electronic, with gains through out the rpm range. Another test showed similar gains.