Rim brakes are very good, and as addressed earlier, there are some ways to run bigger tires with them. I have a bike with carbon rims and old Weinmann rim brakes, but I would never recommend it. Cable actuated discs are very good, also. In my opinion hydraulic disc is the only way to go on anything remotely new and nice, worth every penny.
Aero disadvantage and weight of a disc set-up (I'm dubious of the 2 pound claim) will not get you dropped on a local ride or race, you will get dropped because you burned too many matches or are simply out-gunned and out-motored.
If you really like sprinting, after you get your road bike get a track bike with front brake and an 85 inch gear or so, for fun and road sprint training (assuming you have flat to gently rolling places to ride)