Definitely go with the cyclocross bike. I have one and have taken it on and off road. One of the reviews I read had taken in through a tough mtb trail and said it handled really well. And of course it does great on the road. I only have one bike and use it for everything from a two mile ride to the pub to a 40 mile sunday ride. The plan is eventually to use it to ride the CA Aids Ride which means I'll be doing century rides on it.

As for the breaks, what I've been told is that disk breaks work much better in wet conditions than normal breaks. I've never had disk breaks and I've never had any trouble stopping regardless of road condition (sleet, rain, snow, dry, mud) but they may let you stop quicker than normal breaks.