Ah, I didn't know that it was possible to use one's own PRIR with the software. I can also see the point that other people may have a better chance of finding a "matching" profile, but from my experience with the Realiser and foreign PRIRs is that even if you find one that works well, the result is still below of what's technically possible.
@darinf, your comparison to a pair of jeans is a bit unstable - as of now, the hypothethical brand only offers only a "one size fits some" model. If you can find a way to make HRTF adjustments (as well as Headphone EQ) that would solve the majority of problems and create a really great product.
Don't get me wrong, I appreciate the concept of your software and think it is to be applauded. However, as it's a commercial software I feel free to criticise it openly. By the way, what about licensing? Strictly speaking, you are using Smyth technology in your software - please correct me if I am wrong - is there some sort of agreement?