In the $700 price class there is some great competition.
SVS PB-12 NSD
People are going with known entities at that relatively high price point. If we had some objective testing we could make some comments on the Earthquake, but I don't see any testing of that model on their web-site.
It sells for under $500, but that still puts it among stiff competition. The only insight I can give is the enclosure is to small (1.8ft3) for what looks like a pair of 3" ports to be tuned lower then 30hz.
There's an internet wholesaler that sells that FF12 for $350 with a 15% coupon if you ask for it. Ended up getting mine for $315, and I think it sounds pretty good. It rolls off heavily below 25hz, so don't expect much it to play loud at 20hz. If I had to do it all over again, I'd go for the next class of subwoofer in the $500-600 range.
Wish I could give some measurements, but I don't have the equipment to do so.
It's nowhere near $700 - more like half that. You might want to hold off if you're thinking about getting one though; they're in the middle of redesigning it now. The new one will be more along the lines of the FF6.5 and the FF10. It should be released before the end of the summer.
If you take yourself too seriously, expect me to do the exact opposite