I like the Cannondale disc brakes. It is not unusual for us to climb - and descend - 15-20% grades. Some are long descents where I'd be pretty nervous about rims heating up; Palomar Mtn tomorrow, for example!
We use the Chris King headset but it's not a cost-effective upgrade over Cane Creek or FSA. A better upgrade would be TRP Hy/Rd brake over the BB7 or Shimano R515. The Hy/Rd uses dual hydraulic pistons, which are more powerful and self-centering.
My understanding is that the punishing Mt. Washington has an average grade of 12%, with a 50-yard section of 22%. Would be nice to have full hydraulic brakes when the average grade is 15-20%.