Had an '06 Classic I bumped to 103 with some Woods cams and an SE 6 speed. Loved it & put just shy of 50k on it in 3 years.
Traded it in May on a '10 Limited with just a stage 1, some Rhineharts and a tuner out of the box. I have 15k on it now.
The FLHTK is definitely heavier, does not have quite the torque or HP as the old scoot, so it's a little doggier and did a lot more down shifting on the long trip this summer. Definitely going to do some head work and probably throw in some Woods 630 cams. I'm also a little worried about the pressed cranks I'm seeing other friends having a little trouble with.
The good news is, she rides like a dream.....big difference compared to the old scoot. The engines mounts knock out a lot of vibration and shake and my wife remarked there is more room in the back. I think with the changes I mentioned above, we're going to get along just fine!