Are you using your 2012 CAADX to supplement your marathon running, or are you using it supplement your bicycle upgrading/mechanic skills?

If I were you I'd spend more time riding the bike you have rather than spending additional time and money on the seemingly endless "bicycle upgrade/weight loss treadmill."

You can later buy a lighter bike if you decide to "get serious" about CX racing (as others have mentioned). Besides, it sounds like you have a competent multi-purpose bike as it is.

Also keep in mind that good bikes, with expensive upgrades, are often more likely to be stolen, or stripped of their components, while parked in public spaces.

Anyway, welcome to the Bike Forums omarcastz, and good luck with your new sport.