@shadyJ
I'll do an experiment, it's subjective, but you do raise a good point. I'll incorporate a 20 low shelf which will kill anything that is happening below that, and test the difference just using my ears with F* Irene. I might even do the same at 16, 12 and so on until I just don't hear/sense/ESP(or whatever lol) the sound is doing in a beneficial way.
Of course this begs the question, have you done anything like this?
Mark Seaton did and he claimed his test audience preferred the lower end extension. Of course he has the Earthworks 9000 (or whatever model) and his knowledge qualifies as you detailed. He also has subs to sale but I don't associate him with being the least bit dishonest.