If the OP likes his Klipsch there is no reason for him to not get another. Getting a different sub, especially from one of these on-line only companies can be intimidating. I don't personally like Klipsch subs because they have rather resonant cabinets and weak amplification for their size, which they can sort of afford to do with driver efficiency. The Klipsch lower line subwoofers have trouble hitting the lowest of lows, and that would be another good reason to get a different one.
But, like I say, if the OP likes Klipsch there really isn't much else to be said. We could easily turn this into another SVS/HSU thread (and it feels like that is were this might be going), but I don't see how that is necessary. Just because one person or many thinks that Klipsch is not of appropriate quality shouldn't warrant "just sell it, and get a SVS or HSU". I am guilty of doing this as well, but I am going to try not doing that so much.
End rant...