Here are some excerps from that link.
16. Axiom EP-500
Listening results: The EP-500 was one of the first subwoofers to stress linearity across its frequency band. What is somewhat ironic is it sounds more like the baby brother to the new PB-13 Ultra than do smaller SVS models. It is capable of surprising amounts of bass slam, and is excetionally articulate for music. Its down side is that is current price is rather expensive for the performance. Its up side is it is quite compact, and an excellent choice when space is a consideration.
Measured results: 20 Hz ... 97 dB ... 20-63 Hz average ... 107 dB
15. SVS PB-12 Ultra
Listening results: A terrific subwoofer considering its 2002 design. It remained competitive in the $1200 - $1500 arena until 2007, when it was replaced by the PB13-Ultra. The "old" Ultra was at one time a standard bearer for performance, and remains a solid mid pack subwoofer today.
Measured results: 20 Hz ... 102 dB ... 20-63 Hz average: 109 dB
3a. SVS PB13-Ultra
Listening results: This subwoofer delivers incredible performance from a moderate sized box. It is almost on par with the larger Conquest and eD subs in terms of delivering palpable bass, and it is as articulate as the standard bearer Fathom 113. A great choice when one is looking for a combination of reasonable WAF and performance.
Measured results ... 20 Hz: 108 dB ... 20-63 Hz average: 113.5 dB
