Since I haven't listened to any, I'm going to have to go off of other people's opinions...and after reading enough, I can paint of picture of what I think I would want. This is why I am in the JTR Noesis thread because everyone painted pictures with their own special words that made me think...this is the speaker I want...even when I didn't think I needed to upgrade my current speakers.
So when I think I want high sound quality subwoofage with solid, deep output (10Hz near reference), I think LMS 5400. Others are good too but the LMS 5400 seems to float to the top as being some of the best. Obviously Submersive, Caps, etc. also fit in that realm but I'd like to go the DIY route and it is harder to get a "picture of words" of what some of the other subs are like in comparison.
Another sub that I am drawn to because of sound quality is the Rythmik FV15HP (again, I haven't heard it). So would 6 (six) FV15HPs at 12Hz tuning give enough output to be able to demo Noesis 228HTs every once in a blue moon with normal listening levels being more pedestrian. Mainly because my guests likely won't want it that loud and I don't want to destroy my kids hearing. Let's say 6 FV15Hps compared to 3 LMS 5400. Again, my room is 1800 cu.ft. open to a similar size kitchen in the back.
And no Popalock, I was thinking your 16 subs is the Bugatti...and apparently I'm looking for an entry level sports sedan.
Thanks again for the discussion in the JTR Speaker thread. I'm getting great feedback from people whom I've read lots of their comments over the last few weeks/months and helped me paint the future picture (almost) of my home theater living room. Much respect!