Can you comment on the aero impact of 25 mm in rear vs. 23 or 21? Is a 25 mm in rear with a 23 mm in front "significantly" (purposely ambiguous) worse aerodynamically than 23 front and rear? Does the width of tires (front or rear) have an effect on crosswind stability?
How does crosswind stability of 6.7s compare to low profile round spoke wheels? To 3.4s? To what extent does rider weight affect the assessment of crosswind stability?
We didn't do any testing with different front and rear sizes. Tunnel time is pricey, after all. Had to keep it limited.
The 6.7's will still kick you around more than a traditional wheel. But, unlike the old V-shaped stuff, you can ride them in pretty nasty crosswinds without any real issues. We get very, very strong winds in the spring (usually a day or two with gusts up to 130kph, and lots of days of 50-60kph+). Normally I don't ride deep wheels much at all in the spring, but both the 6.7's and Hed 6's were fine up to about 40kph crosswinds.
And now in the category of always wanting more, have you considered evaluating some wheels not marketed as aero by the same methodology - of course, for wheels lighter than Bontrager, you'll have to change the weight score formula (maybe just go up higher than 5?)? In particular, it would be nice to see Enve 3.4s, non-Smart Enves, MadFibers, and Lightweights (Standard/Oberymayer and Ventoux) evaluated in this manner. Even if they're not being sold primarily on their aero attributes, it's nice to know how aero they are, stability in crosswinds, etc. Might some manufacturers not want to participate for fear of not looking good?
We don't have a pressing reason to evaluate wheels that are sold without aerodynamic claims in the wind tunnel. It's expensive, which is why we're one of just a few mags in the world that do it. The purpose of this test was "if you want the best aero wheelset, which should you buy?" It's pretty clear that Lightweight, old V-shaped wheels, etc are probably not it...
Although I do agree that it would be interesting to compare, it doesn't make a whole lot of sense for us to do it.
For the question about tire size used, it was just a way to normalize. We tested each wheel with 21, 23 and 25mm, actually, and the ranking was identical. But with minimal space in print, we weren't going to publish all those charts.
And yes, you are correct regarding the Enve wheels and WI hubs. When we first received the wheels they were offering those hubs.