My first system was the Klipsch Quintet series (with sub-10) and i really liked the set-up. The sub-10 sounded nice in a 15' x 25' apartment living room. However, I ended upgrading my sound system months later to Klipsch floor speakers, bigger surrounds, a center channel, and a bigger subwoofer. So my advice is... if you plan on upgrading your Klipsch system, then I would highly recommend getting the sub-12.
Good luck,