There is a lot behind those specs, and a lot of ways to misread those specs. I can only say a few things. First, don't pay too much attention to wattage, either RMS or short-term. The system type (ported or sealed), sensitivity of the driver, and enclosure size have more to say about overall performance than how much wattage is on tap. Second, driver size can also be misleading. Just because a sub has a bigger driver does not make it a better performer, much like wattage. For example, that 13" driver on the SVS is a real beast, comparable in performance to many 15"s. On the other hand, some 15" drivers out there aren't all that amazing. The Hsu sub has a pretty good 15".
If you are primarily interested in performance, you should be looking at performance measurements rather than build specs. The most commonly used performance metric for subwoofers is called CEA-2010. This metric shows you how much output the sub can produce within a certain distortion threshold for a certain frequency. Hsu has these numbers on their products page and the SVS numbers can be seen in reviews. Keep in mind that the Hsu sub can be configured to run in single port or dual ported operation, and this does change the potential performance. I'll make it easy for you and just post a table, since some math has to be done on these numbers to make them comparable.
Frequency (Hz) | VTF-3 mk5 (1 port) | PB-2000 | VTF-3 mk5 (2 port) | PB-3000 |
16 | 99 | 93.8 | 97.8 | 96.2 |
20 | 105.4 | 105.1 | 105.2 | 108.3 |
25 | 110.1 | 111.8 | 110.4 | 113.3 |
31 | 113.6 | 113.2 | 115.2 | 114.9 |
40 | 117.1 | 113.7 | 118.9 | 118 |
50 | 117.5 | 113.6 | 119.3 | 119.6 |
63 | 116.8 | 113.4 | 118.1 | 118.6 |
80 | 116.4 | 113.1 | 117.4 | 117.8 |
It should be mentioned that these numbers aren't exactly comparable since testing conditions can change somewhat from test to test, but I would say they should be good within +/-1dB.