It sounds like the steerer on the Jamis' fork is also carbon. Big thing is to shave weight, but I've never ridden a bike with anything besides a metallic steerer, so I can't comment on that how it affects the feel.
If you want to use it for light touring...I'm concerned that these are race-oriented cross bikes. Do they have the appropriate hardware to let you mount a rack if you so chose?
Beyond the weight savings, I'm not sure if 105 offers a huge advantage over Ultegra. Some people say they can't tell, some people say they can. I'd be tempted to go with the Ultegra just so that you wouldn't have to eat the extra cost of upgrading later if you wanted.
The BB7 brakes are a known quantity to me (contemplating upgrading the ones on the Charge to those later). The Cannondale ones are not.
That said, I had been drooling over a CAADX at one point. No idea that they'd made a disc version. (Maybe for a go-fast cross bike?)
ETA: Going over the component specs, hands down the Cannondale's the better bike. I'm not sure about the brakes, that's the only thing.
Big thing, of course: How's the fit?