As for the rear brake lock-up caution, I can lock the rear wheel on my rim brake equipped bike with 24 year old original pads. I recommend practicing rear brake lock-up so you know how to react if it happens in an uncontrolled situation.
The Fast Lane is a great frame, The OP has done his homework. I recently was present for two builds at an LBS and the workmanship is worth the money if you can afford it.
I have a few very steep descents where the pavement is so bad riding the brake is absolutely necessary. When one needs fade resistant brakes, one wants fade resistant brakes very badly.
I'm in the middle of building up a disc equipped road bike, I don't have first hand riding experience just yet, but I am going through the component selection process. My rear spacing is 132.5, I've chosen a
Velocity road disc hub 130 axle rear, and
Velocity Light Weight ATB Disc front. I must spread the rear stays on my current road bike to R&R the rear wheel and I'm weary of that inconvenience, I'd rather the wheel go in easy and the scewer nut do the work (at least that's the plan). The wheels are a
custom build, which makes them a little more costly. Brakes are BB7 Road. I couldn't afford the Gunner, my
frame geometry is slightly more cyclocross/commuter than road/touring like the Gunner.