Do you mean VTF-2, not the STF-2? The VTF-2 is about the same price as the SVS sub; the STF-2 is considerably cheaper.
I figured I don't need the VTF line as from what I understand, there is a setting for HT that leads to the sub essentially playing louder but not quite as deep (this from the explanation on HSU's FAQ, or at least that's my interpretation of it). Loud, room shaking bass is not really something I'm looking for. I think the STF line will make more than enough impact so I'll save some money and get that. This is just what I figured - I could be wrong in my assessment though.
You're right in that the SVS is quite a bit more money. However, there are two factors...one, I can actually order it from SVS' Canadian distributor and pick it up myself as they are near by (HSU in contrast I don't believe has a distributor here). I'll save some money on shipping charges with SVS. Two, if that sub offers some sort of performance benefit over the HSU, then I'd have to consider it.
I could get an SVS box sub but my impression from reading about the two companies is that HSU makes a better product, if just barely. I probably can't go wrong either way though.