Be careful with the sub specs, they don't necessarily translate to a better sub, other factors are involved.
I picked the F12 because at the time, it was 183 on amazon with free shipping. While good for movies, it lacks in music as I recently discovered.
F12 has a 5 year amp warranty, the Sub12 a 3 year amp warranty. What sounds better? People seem to think the Sub12 performs better with movies and music. Only thing is the Sub10 and Sub12 series have a chronic amp problem and if you're like the many unlucky owners on Klipsch's forum, your sub might die prematurely and you'll be stuck footing the repair bill. Klipsch's customer service response to the problem hasn't been good, read this forum to see what people are going through to get their sub fixed:http://forums.klipsch.com/forums/p/143115/1461162.aspx
I Good luck making your decision, if I were you, I would check out HSU's STF-1 which is on sale right now for $269. It probably trumps both of these subs, though slightly smaller.