There have been many threads comparing those two, plus the Outlaw LFM1- EX. All three are good subs, each with advantages. They have different configurations. For example, the Outlaw is down firing, so is protected. the HSU has a port on the back but the SVS has it on the front. They look slightly different. SVS has a better warranty. For some people, those factors will decide the matter, because all three are great performers. The SVS has a more linear response and, because of its build and DSP, is pretty impossible to overdrive. But the other two have better max output, spl, at most frequencies except below 30 Hz. The outlaw sometimes goes on sale, which makes it a great bang for the buck deal.
Also check out the new company founded by one of the original owners of SVS. It is called Powersound Audio.