I think it is going to depend on the type of listening that you do and what you want from the sub. The PB-12 will give you more "slam" in that it will activate more air, particularly down low. The advantage of the SB is that it is sealed and small, so you will get a lot of sub in a small space, however being sealed, it won't give you quite the same tactile response that a vented sub will. I think both would do fine in a room that size, so it comes down to listening preference.
