Your comments on the sub are interesting and my observations on bass response are similar when the listening area is up against a back wall. It seems to put a hump before the deep bass.
My new listening room is a large rectangular living/dining combo 16wx22lx9h. My seating is at the halfway point of the long dimension with the dining area behind me. The bass is remarkably even and smooth. At first I thought it wasn't punchy enough but after continual listening it seems to be more accurate as all the musical information is there. Its just not as punchy or should I say boomy.
I have since read in Hi-Fi+ magazine that this is the ideal listening environment.