Kind of makes the lay person (me) wonder what the point of the hooter shooter is. However, it still seems to me like this would be the ultimate proving ground for the equipment to shine, since you have eliminated all other variables, the only variable left to out perform, is the equipment.
The HS is the ULTIMATE tool for sorting through arrows! You go through a dozen of your arrows and see which do not impact with the others- it might surprise you..... It's great for checking draw length, drop-away rest timing, cam timing (once you know what you're doing).
The HS does eliminate on very important variable- the "human" factor. And I think THAT is where the differences in cam systems can show up, and why they may be so elusive to "prove".
I know that the HS can shoot a bent arrow out of an out-of-time bow into the same hole every time. Now, if I try and take that same combo and shoot it, I'll be all over the place and my groups will not be anywhere near the size of my groups being shot out of my well-tuned and primed target rig. Why? The HS can shoot my target rig into the same hole, and I can come close to shooting my target rig into the same hole, but I'd be all over the place with the out-of-time bow shooting a bent arrow.
The human factor starts to get into the grey area of "forgiveness" of a certain bow and arrow combo and/or cam system. How much can the archer's form screw up, yet still shoot an arrow rather accurately? How far from being machine-like can the archer get, yet still group well? What may lend itself to better performance for one archer may not lend itself to another archer because of personal likes, form, style, etc...