I agree, the Kona sounds like a pretty good bike for brevets so long as it fits you well. I have heard that Shimano's 105 brakes are a really good investment and improvement. I don't know about 105's but I rode a bike with Ultegra's Calipers and almost went over the bars due to the braking power.
You mentioned that the cockpit was tight but the reach and stack look generous when compared to the frames I've been looking at for Brevets.