Got my F-12 last Friday from Beach Audio. Coming from a KEF PSW2150, I'm pretty impressed with the low frequency extension and the dynamic power. This thing rumbles pretty well and has enough hit to make you feel it. I haven't had a chance to do really fine adjustments yet, but it seems like this sub will be decent for music, but not spectacular- with only my rough adjustments out of the box, some types of music were a bit too boomy, and others sounded good- I guess I'll need to tweak a bit more to find the best for my taste.
Either way, for the price, I'm happy.