The A2 is not that far away and I think everyone who has been there will tell you it's time & money well spent! See you on the salt!
I've not been in A2, does it run the same boundary suction and wheel rotation systems as A1? If so I would question validity of results specifically in the areas of underfloor flow. Not saying the results are wrong, I have met Gary Romberg before and he is a very smart and cool guy, and I know the tunnels get good correlation for NASCAR, plus I know for what we are doing few people can afford Windshear.
But if you are specifically looking at small interactions under the car then I would suggest that directly sucking the airflow through the floor in the test section is not going to give a good representation of how air moves under a car. You really need a moving belt with the boundary layer taken care of before it gets to the vehicle.
This is something I have worked on, on a number of different race (and road) cars and it does not have a simple answer. CFD is a good tool for it but struggles with accurately modeling splitter separations that occur on real cars, thus you often gain too much confidence in a CAD design only to find you are short on front downforce on the real car. Or even worse the pitch sensitivity is through the roof. The famous flying Merc at LeMans was caused by a pitch change of about 1/10 of a degree!
I have actually been thinking of writing a paper for the LSR community on this very subject to aid teams in designing safer race cars, as of yet I have not found a backer to help with the testing and my boss isn't very keen on lending me the wind tunnel and letting me make a model free of charge.