Would have liked to see some sort of accounting in the "scores" for missed shots.
Also, while the shooters were definitely of varying skill, they were all more familiar with some of the weapon systems than with others. It looked like all of them were pretty used to working the AK and especially the AR while there was clearly some confusion on the part of most of them when trying to get the HK clone (and to a lesser extent, the M1A) to perform.
Rather than trying to get shooters of differing skill levels, it would be interesting to get a group of test subjects who had no experience at all with any of the weapon systems being tested. That would let you know how intuitive a system was absent any experience advantage.
Or, failing that, to compare scores from experts in each of the weapon systems against each other. That would provide information on how well each system performs in the hands of someone who is highly proficient with it.