I've put 14,xxx miles on mine, so far. Because of the cylinders being bored to the max, I've had some cooling issues. Even stock it's always run hot, and I'm running synthetic motor oil, a HD oil cooler and with a good tune. After doing the 107 the overheating problem was magnified. This Summer was especially rough with all the record highs being set in the Midwest. I wound up purchasing Jason's (Wards Parts Werks - Forced Convection System) cooling fans and my overheating problems have disappeared. The is the best 'peace of mind' addition I've made to the bike. In addition I had some starting issues when hot. High compression and a hot engine made the starter 'kickback' and make a terrible (embarassing) grinding noise. (especially on short stops, like at the pump) Leaving the cooling fans running while pumping gas has alleviated the vast majority of this problem as well.
I've got over 20k I imagine. (I can't remember for sure. I posted actual mileage in a thread a few days ago. Everything's good.) For some reason mileage has tanked recently. Just got back from Brookings, SD and was only getting about 33 mpg - down from 42 or so. Gotta go check plugs after it cools off and see if they tell me anything.