paradigm servo 15 v2 for a small room.

Perspective from a pro AV systems designer, long time AV and hifi hobbiest here.

Everything should be kept in balance. And with rooms/systems, balance is key. There are plenty of reasons that you should consider smaller speakers and a smaller sub combo in such a small space. Without going into all the details, the short version is that you should keep all the speakers in proportion to the size of the space, for best sonic (and visual lifestyle) integration. Short form, is that 5 to 7 small satalites, and medium sized sub, integrate much easier into that sized room than does 5/7 large monitors and a big sub!
A room that small doesn't properly support deep bass anyway, has limited bass absorption capabilities, and could use less bass energy, as a whole, because of that. Also, I recommend people steer towards piston type speakers with 5.25" drivers as a maximum, because they integrate better typically into the small room space, response wise (typically), and are less boomy overall. Basically, they just seem to sound more well balanced, when setup up right, in small spaces, exagerate lower bass modes, a bit less, usually offer better off-axis sound, yada yada.
Then, becuase you are going to cross the speakers over at 80hz, a smaller woofer tends to also cross over higher and integrate with satalites much better than larger counterpart woofers.
Bottom line, that 15" sub is much better suited to rooms that are at least twice as big as yours in my experience. And I really like that Paradigm sub! It's a terific tool. However, like any tool, it needs to be implemented in the right setting, in the right system and room. And I would not shell out $1200 for a monster sub in that small room. You don't need it.
I would much rather see you with something with a 10" woofer, and properly integrate it into the space. Dual 10" woofers even. And then you'll be EQ'ing the woofer ultimately, sure. Still, stay smaller woofers. A single is more than fine in this room. It will play hard and deep (enough)to do the job. No, it won't play down to 5hz. But then so what?! Balance and quality over quantity.
You won't be using anywhere near the potential of that large Paradigm, it will be way too much bass energy and boom for that space (you'll need to really EQ it hard. And even then, you'll have too much reverb energy down low, making the space sound too warm, thick, and sluggish and boomy in the bass).
Yes, go with something like the Paradigm PS1000 in that line, or similar. If you have to spend more on better subs, go small power-cubs with higher watts, Earthquake 8" or 10" models, Sunfires, and other small sealed woofers.
Lots of offerings from a near infinite amount of manufacturers. So do some research.
But, I vote NAY on the large Paradigm for now. It would be the equivalent of putting a 350cu inch blown chevy into a VW Bug! - you wouldn't do it.
Save that one for a larger space, and save some money!!!
Basically, I've been doing systems for decades now, and I wouldn't go Servo 15 in your small space - even though it's otherwise a superb (one of my fav's) woofer, on it's own.
Nope, wrong fit...
Good luck

"Just because you have a large sub doesn't mean it's going to be running flat out. They don't need to be used to their full potential to sound correct".

Fist thing off the bat is that I 100% guarantee you that abzolutely zero professional av reviewers or system designers are going to use or advocate that large servo 15 in your small space...ZERO! The reasons being what I mentioned. Your large servo 15 and small room combo will be boosting the bottom end of the 20hz extension of the servo too much, and exciting the 40hz, 47hz, and 80hz mode from the sub. Yes, you'll eq em, and also have to knock down the entire output from the sub bellow 40hz by enlarge. And you'll not be getting the benefit. Also, the large 15" driver is NOT going to integrate well with your satalites, period! A smaller woofer will do this much easier, allow for higher crossover if needed, etc.
A smaller 10" woofer system will naturally roll off at the 40hz reigion usually, which integrates into the room better to agree with the natural boundary boosts better - for smoother response, won't unecessarily exite the lowist bass mode, etc.
The large 15" woofer/box combo will barely be tapped for it's potential, wasting money and it's size. The smaller woofer will be better used to it's potential, still offer all you need in terms of dynamics, integration with satalite speakers, and blend with the room best - without having to EQ the crap out of the woofer, and for what?.

" I had two 18" Servo Drives in my smallish HT room for a month and they sound great." "Room nodes need to be addressed by means of EQ, multiple subs, and /or room damping.

If you hear this set up in a small room, the room still sounds small and overly bass heavy, sluggish and warm, with lots of bloat and overhang (reverb) in the bass. The room dimmensions are too close, and you'd have to build a massive bass trap in the next room or ceiling to absorb all this excess energy high quality bass performance. This is not practical or possible for all but a rare few instances for most. So "room dampening" can't really apply here likely, I'm certain.
These small rooms sound SMALL and boomy because they can't absorb the bass properly. So adding maximum bass volume and extension does nothing to help the acoustics here. And even the well touted Audyssey can't do anything to aborb all the excessive bass and RT curve. In short, it's low fidelity on the bottom end - not productive to hi-fidelity sound.
If you wan't to have a bass heavy boom-box sound from your room, that offers low fidelity bass, then this is the recipe. Again, balance is how you build any high performance race car, world class gormet food recipe, diet and lifestyle, and world class audio system.
If you still think you should get away with using massive woofers in small spaces, don't take my word for it, just simply email every pro AV magazine reviewer and ask em what you think about putting 2 Velodyne 18's in your 12x14 space, and see what they recommend back. Then you'll get a more concrete professional feedback.
Let us know what they say...if you really want to know, that is.

Well here you go. Just email www.rivesaudio.com or www.pmiltd.com, and ask Richard or Anthony how they feel about your large 15' and 18" options in your space/application. I think you know what these professionals will say here, basically, before you even email them.
If it were me, I'd be looking at $100 budget subwoofers, used on the net. You can then put your budget towards much needed room acoustics and quality monitors and equpment, instead of wasting $1200 on an ill-fitted product that doesn't match with your needs. Leave that to the less edjucated types - who drive around town with 18" woofers in their Honda Civic's, poluting the neighborhood.