Subwoofer Decision

I have narrowed my search to two choices though I am sure I will get comments steering me away from these.
Contrast Rythmik Audio 12G with Vandersteen 2Wq. I would like to get only one though I know a pair are best choice. Could maybe afford 2 Rythmik, but only 1 Vandersteen for now. The subwoofer would support Dali Helicons (4 ohms) biwired and driven by 2 mono McIntosh MC 252's at 500 watts each into 4 ohms. Living room size aprox. 24'x16'x8' placement not centered on 16' wall due to furniture (wife) constraints must stay put. Subwoofer placement needs also to stay there as well, I know this limits possible best choice for placement, my bad. There is room behind, next to, and between speakers. Any help help is appreciated.
773de154 8d26 4ee0 97f3 40a97799ea35lowfreqguy
Check out HSU ULS-15 MKII
Excellent price, excellent performance!
I am running two in my system and could not be happier.
The "slow' vs "fast" issue regarding subs is especially strange and inaccurate. Bass note "hangover" is generally the room continuing to resonate from low tones (unless damped by rugs, extreme cobweb infestation, bad furniture, or your fat cousin Bob) which is what low tones do, and it should be noted that 15s or 12s or 10s or 8s all respond to bass amp commands similarly (although I like the REL main amp derived method), and when those low notes wind up at your ears it's not due to "speed" at launch as that's just a lazy non technical comprehension catch all.
Best bass driver ever made is the Danley/Eminence designed and built by Eminence LAB12. It's in use by all IMAX and OMNIMAX theaters. Get any subwoofer using a LAB12 and you're set.

One example would be the BK Electronics Monolith Plus. Which also uses a 500 watt MOSFET amplifier. BK used to be the OEM manufacturer for REL. They were responsible for the ST range (Strata, Storm, Stentor, Stadium), which made REL famous worldwide. REL makes Chinese crap now. 

BK has my vote as the ultimate internet direct subwoofer manufacturer. If I had to choose another company, it would be HSU.

As for Vandersteen versus Rythmik, Vandersteen destroys it in every possible way. 
I have a pair of Hsu subs for my office. They are good, but not as good as my Vandersteen 2w's.