Are big subwoofers viable for 2 channel music?

In thinking about subwoofers to get for a large future listening space (30' x 30'). So far there seems to be a lot of great options for smaller subs for music.. such as the rel s812. Now my main focus will be music but I do plan to do some home theater on the system and I do enjoy subs that reach low and have strong but clear sub-bass. Would a large sealed sub still be able to provide clean tight bass that digs low and thus satisfy both duties. Can it ever match the speed and precision of a pair or more of rel 812s? Something like PSA S7201 or Captivator RS2?

A realize a smaller sub has a smaller moving mass and thus for a given level of power would be faster than a bigger sub with a bigger moving mass (driver mass). But a large sub would have to move less to achieve the same SPL and would reach lower.

Anyhow what do you guys think? Thanks.
I have a pair of REL 212s, main speakers with their own powered subwoofers. So far the best sub position has been to place them just a bit beside the listening position, slightly to the rear. Without one of the various room measurement programs everything seem like a crapshoot. 
Not to say they haven't improved the bass and overall presentation, but there remains questions as to whether they are optimized. 
Thanks guys lots to think about.

While a pair of Rythmik F18’s is undoubtedly awesome (I say that being familiar with the F15), a quartet of smaller subs (say, the F12) may be even better. Place two of them as close to your listening position as possible, to maximize " visceral-ness".

The F12 is available with either an aluminum cone, or a lower-mass paper one (the F12G). The F12G has been optimized for music, the F12 for all-around use. Get two of each!

If you find the dual-opposed design---popularized by Seaton---appealing, check out the newish Rythmik G25HP, which I would much rather have. The Seaton is just a couple of woofers in a box; fine for home theater, not for music.

If you've got the dough! Brian gives a 10% discount on multiple sub orders. That'll help: the F18 sells for $1630-$1850, depending on finish. Sure, why not? You have a big room, so you don't have to worry about overloading it.

All the Rythmiks share the family DNA: detailed, nimble, no overhang or slop (they're described as "stopping on a dime"). Lean & clean ;-) . And they all play into the teens. The difference between models (other than the unique OB/Dipole Sub) is in their maximum output capabilities. The F18 puts out 114dB at 40Hz (1 Hz below the lowest note produced by the standard 4-string bass) with less than 5% distortion, and 99dB at 16Hz (the lowest note on a pipe organ's bass pedals) at less than 20% (in the world of subs, that's low distortion).