Congrats on your purchase, I'm sure you won't be disappointed!
I haven't tried any of the SVS subs, but have heard nothing but positive things about them. If/when I decide to go with something bigger, I would likely buy one of their big guys (I've always dreamed about having a refrigerator-sized sub!!!)
I've owned a PSB Subsonic 6i for about 3 years now - I purchased it around this time in 2004 after reading the "Sesimic Subs" test in S&V. I bought it because my Mirage BPS-150i (tight, fast sub, dual 10" inch bipolar, sealed config, excellent for music, was about $1200 in 2002) was having a lot of difficulty filling my >7000sqft great room with the long, low rumbles often found in movies.
My original intent was to buy the PSB and add it to the Mirage just to boost movies (the Mirage handled music fine). I didn't think the one sub alone would handle the room. Boy, was I wrong! The PSB not only shook the house and handled anything I threw at it, it also turned out to be fast and accurate enough for music... the Mirage sat around unused for a few months before I could bring myself to sell it.
I now have the PSB in a <5000sqft carpeted basement room, and it has no trouble at all hitting very high SPLs in that room. I watched War of the Worlds last night and it was pretty incredible.
In neither room was the sub corner-loaded... it has always sat to the right of my left front speaker.
JVC DLA-RS2, 120" Grandview motorized screen, 60" LG 50PN6500, Marantz SDR7007, Energy RC-70 mains, RC-LCR centre, RC-R side and rear surrounds, dual PSB Subsonic 6i, Sony BDP-S5100, Toshiba HD-A30, Xbox 360, Marantz CD6005, Yamaha CDC-675, APC S15 power conditioner and UPS, Monoprice interconnects and 12GA speaker wire, Palliser Media & Ikea Poang seating
For sale: Denon AVR-3310 7.1 receiver, Adcom GFA-555 and 545 mk2 power amps