I'm in the process of upgrading my sub and had the opportunity to listen to the SVS PB12-NSD. From what I've read, and now from hearing it, I'm ready to buy. As a plus, at $600, it fit's nicely into my price range. However, at the same price point I can also get the SVS 20-39 PCi. Can anybody help me sort out the differences between these two subs and the sub style? Is it mostly a matter of size and weight, or is there an actual sound or feel difference? I'm not adverse to having a 39inch cylinder in the corner.