One Fathom 113 or Two SVS PC-Ultra Subwoofers

I am trying to decide what to do here. I think cost will be the same with shipping. I just don't know my room size because I will be moving to a new city. But I do not have a dedicated home theater room. I just have a living/dining room where my piega home theater is set up. What is your recommendation?

My first default is two quality subs, even in stereo! The benefits in efficiency, distortion reduction, possible room-mode smoothing, and flexibility makes this avenue a plus in my mind! Plus I don't like spending $3k for a sub, when I have have two for the same price. But,that's me. Some like having shinny new toys that are more "collectors pieces" and "show-off fluffyage" than anything! I like bargains,performance, and options.
Yeah, my first thought for you is two Paradigm Servo 15's for the same money - cause I know they'll sound superb for HT/music!
Since you don't have a clue to your room size it is a tough call. Just one SVS properly setup can have heart pounding bass!! These subs aren't for the faint of heart. As mentioned above the Paradigm 15's are nothing to sneeze at either. No comment on the Fathom I haven't heard it.

The safe bet is one until you get an idea.These subs are the real deal! Oh yeah ..the SVS isn't exactly a small sub.I haven't heard a small sub that could truly replace a sub with real volume. There's always a compromise some pick your poison. Not sure how it will carry over with your wife. Performance wise..if she's an HT buff..she'll love it.
Well, not having heard the JL's, my first thought is "Nice Ad's" in the magazines. They at least talk a good schtick!
When I saw their ad for the new F212 sub, my impression was that they were presenting it like Nasa had designed it, Ferrari had built it, and Metalica's Lars Ulrich was endorsing it!
Well I've sold Thiel's, Wilson's, and Entech's subwoofer's over the years, including the large Woofer Towers from Martin Logan. And make no mistake, one (or two) several thousand dollar subwoofers IS NOT going to make your system "world class!", by itsself - for the record. And I certainly wouldn't be running out to upgrade my system with any such things, ASAP, in hopes of moving one rung closer towards championing the worlds greatest audio systems!
But, I'm sure they're nice pieces, and likely good tools to work with. I'll have to try one some time, and certainly look for a JL setup at the next "Show" that comes around.
Till then, it's just another product to be properly or improperly integrated into an otherwise, hopefully, well thought out and executed audio system.
From a performance perspective in the lowest octave, it's more like one SVS PB13-Ultra to two Fathom 113s. If we're talking about above 30Hz at below 100dB, they are essentially equivalent. When pushed harder, the SVS out performs (as expected - bigger box and ported). I can send you the links to the measurements. I didn't post them here, because other posters take issue with it.
Might be worth waiting for and auditioning the coming Emotiva subs...should be major for the money. Offers are a single powered and a double setup w/ outboard amp. Very state of art features as well.