I think the reason velodynes cost more(apples to apples) is because your paying a premium for brand name. I own a pb-12nsd/v and it is a powerful beast. my room is about the same size as yours but it opens to the kitchen and hallway, still this sub has no problems shaking walls, my couch or me!
with music in stereo playback it's very subdued(no pun intended), its very transparent, very natural and doesn't add it's own soundtrack. i really recommend this sub, it goes for $700 dollars.