I hear ya! I know with my rig, the same was said about not needing a sub. And though true to a certain extent, even the Phil3s that are F3:25Hz still benefit greatly from my X-13s.
I've heard it said that Dave is working on an upgraded tower and am curious if it will employ the woofers he's using on the new S2... the Seas Curv cone mounted on their Extreme-class W motor. People that have heard both say the newer S2 truly rivals the BMR's bass response, if not possibly besting it. If he redid the Sierra Tower to drop, possibly, into the Upper 20s while maintaining the accuracy and flat FR both he and Dennis are known for.... That becomes a very formidable tower!
As it stands, I still feel bad a little that I didn't get to hear those before I bought in to Dennis' gear. I will right that someday; soon, I hope!