Never forget that boards are lot about personal opinion. If you love yours, no need to be upset with this particular test result. I have a Q76 myself that works perfectly for me, including when squishing out tight bottom turns in small waves. In fact this is for me one area where it excels the most. And if you read the test, they like it a lot for everything else and the test also "proves" the convertible option is far from a safety afterthought.
Personally, I think that there is a very special type of bottom turn technique that can provoke an unpredictable behavior with the Quads - a combination of more power than most would put in and at the same time a back footed approach. I'm willing to claim that very few sailors will be able to provoke that behavior. And if the particular board has some fin alignment problems or something this may get a more pronounced problem. The fact that they thought the 15/12 fin combo didn't work well for straight line sailing for me indicated that there is fact may be something fishy going on. For me that combo is still like a train upwind (and that hold even for the smaller 13/11 combo which I use a lot).
So I don't think there is a reason to discredit the test or the test crew. These particular sailors probably just happen to tango well with the special feel that is inherent in all quatro boards. Other test teams may have other preferences (and like you say, all others have loved the Quad 76 - I know that testers also from other mags have chosen the Starboard Quad 76 as their personal board). It is almost impossible to be perfectly neutral and don't let your own style and preferences influence your opinions on a board.
And regarding the "trendy kids", I suggest to just show them on the water that your board rips.