"I do not have experience with disc but from what I can tell they perform better than rim brakes."
They don't except under very specific conditions such as in the rain or coming down a steep 15 mile descent. I ride both on the road, my 105 rim brakes are every bit as good as my 105 disc. One major advantage to disc is assuming there's frame clearance, it's easy to squeeze in larger tires as you're not fighting the brake for clearance. Another advantage to disc is it's the future and we've maybe hit a point where it's somewhat easier to find road wheels for disc systems than rim wheels.
Reasons to upgrade: 1) Save some weight. This might be noticeable with better and lighter wheels on a higher end bike. The wheels on the BikesDirect bikes are always the weak point (this is the case on about all of the less expensive production bikes) as that's where they save some money. So pay attention to what wheels you get on the Bianchi. 2) Ride quality. Only you can tell if the Bianchi is "better". In theory, a frame like the Motobecane is a 2nd tier frame, maybe less refined in terms of ride quality as compared to the Bianchi. I ride a 2nd tier carbon frame and find it very stiff, but like the fit and feel otherwise, maybe someday I'll upgrade the frame, not sure. 3) Parts and group, moving from Tiagra to Ultegra where you might notice the difference. I used to use Ultegra exclusively then went to the 105 group and consider it to be the best functioning for the money group out there. So that's a good price point