Well when you get into comparing RAW and go to 1600 ASA, you will find that the Pentax is quite a bit sharper with less noise ...
Have been looking at the K5IIs and some samples you can get on the Pentax forum are simply mindboggling.
In case you are wondering: I have been using Nikon since 1986 and currently use a D300s. But can see the 7D as well as the D7000 and the K5 quite a few miles ahead now of the D300(s).
Met a guy with a K5 and the 77mm Limited Edition lens, thought that was actually very, very nice, not enough, you are right about that, to change a whole system, but nevertheless impressive!
Cheers
Deed
Not even close to enough reason to sell thousands of dollars worth of equipment for a minimal gain in performance.