HA! I am one of the converts Worf was talking about. I just recently purchased the HSU VTF2 and it is amazing.... it's with in your budget ($499). I don't think you'll be disappointed. I've never heard a SVS sub though. Have read lots of good things about them too. I don't know how the cylinder sub is vs the box, but I just didn't look at them much simply because I didn't like the look (hey - I'm a girl, so I'm allowed to care about such things!)
I did go listen to a Velodyne (don't know if it's the same model you mentioned) but the HSU topped it, easy.

And Worf - I'm not tired of you recommending the HSU's.... in fact I think I'm on your bandwagon. I can't shut up about them! Good luck jschaudel. Let us know what you get.