Invite me to join!
Seriously though, it could be one of the most valuable public facing blinds ever done. I don't like the vertical placement idea now that you've said that's how you're gonna do it. If you do do it that way, don't tell the people ahead of time what the orientation will be.
I like the idea of using integrated/EQed subs to take the bass out of the equation.
My biggest wish for the test would be for you to involve as many people as you reasonably can. The more people you can get, the more valuable the data you can provide will be.
One other wish(though this somewhat goes against the Harman science) is to do both a mono and a stereo test. I fear that with 2 very neutral speakers like this, the mono test may end up being just a battle of dispersion width). No real science to back that fear up, but it did show up a few years ago with a blind I hosted between the Revel M105 and JTR 210.
If the same speaker wins both tests it will add further credence to the Harman mono vs stereo science.
Finally, how do you plan to switch and level match? In the past blinds that I've hosted, we struggled to have reasonable switching times with passive vs. active comparisons. Passive vs Passive or Active vs Active was no problem, but we had to resort to very slow manual switching/powering/changing input/setting volume. It made it very difficult to compare.
A couple months ago I hosted a blind between the Revel M105 and JBL 308p, but it was similarly painful. I asked ahead of time if any one knew of any device that could switch between passive and active. I did get some responses, but the cheapest device was like $1,000. At 5x the price of what I paid for the JBL, it just wasn't worth it, but for a $30,000 blind like this, it might be.
*Edit - Also, take in room measurements of both in the same spot.