While I absolutely love the rear, I do have some reservations about the front.
Before I changed the front to a K60 I had a K60 on the rear and a worn Dunlop 606 on the front. This was a pretty good combination and especially good on the dirt. The combination felt very predicable and secure.
The front K60 seems very good on tar, but it doesn't feel that great in gravel. I also had a near tank slapper on a clay based road just after a storm ... that has never happened before with the 800.
Unless my opinion improves, or the life is extraordinary when I wear out the front I will replace it with a TKC80, but will use a rear K60. I may even see if I can do a deal with a local dealer and see if I can trade the front K60 on a TKC80. I rode an 800 with TKC80's front and rear, and while the rear didn't impress me that much, I thought that the front was very good.
So summary ... K60 on the back, TKC80 on the front. My AUS$.02