You might have considered this already, but just want to be sure. Try not on buy HT equipment on where you live now (especially if you are renting- not sure if you're renting or not). The reason I mention this is what if you buy a smaller sub just to please your neighbors. Then move to a bigger place in the near future. Just my $.02!

Regarding the smaller subs (around 8"). I checked out the Def Tech PS80 and the Canton AS22. I ended up going with the PS80. The Canton was nice, but inferior to the PS80 IMO. I don't know much about the Hsu, but from what I read, it seems pretty nice! Fyi, the PS80 retails for around $350. Please do not pay that price. I got mine for $275 from an authorized dealer. If you have any questions about bargaining, please let me know.

Good luck and enjoy!
Eric