Not dispersion related but just a thought. Have you heard your speakers with a Peavey CH-3? I own some CH-3's and I have used some H-290's with the same speakers. While they are amazingly similar despite their appearance, I felt the CH-3 had more body and the H-290 had hotter presence range. I consider the CH-3 to be pretty neutral, while my impression of the H-290 was leaner, dryer and cooler sound. It may be a subjective taste thing and humans are full of opinions, but it was obvious to Jennifer and I. The CH-3 might sound like backing off a few feet from an H-290 to some folks, Maybe you.

You would have to get screw-ons, but I think you would like them. To many these differences might be hair splitting, or trivial. If memory serves me, there have been a few specifics you have dialed in to what some would say is the hair splitting realm, which you noticed and appreciated. This "slightly" different horn may be just the ticket. One look at the throat and you will know you have never seen anything like it, in a good way. Do you know a nearby Pi guy you could trade horns with for a couple of days?

I wouldn't want my armchair evaluation to get you spending money and not liking them, BUT I still feel based on what you said in SET forum that you will like CH-3 better. While I am still using 2370's for the incredible off axis top octave(lots of spread out chairs in here). Other than that 2370 sounds about as good to me as the CH-3 when compensated accordingly, but it's not a better horn IMHO. If they weren't so pricey on the Theater 4 scale I would suggest them as well.
Thomas