I went from a brand new K900 (one year owning with about 7000 miles ) to a brand new Cadenza full load and I took a hit . Having said that I like the Cadenza much more for a number of reasons .First and foremost the screen is not touch controlled .All commands come from the Joystick. Simple things like locking in radio stations are a real pain in the *** . Secondly ,it ate gas like a sieve .I drive in the city with no freeway driving and stop and go mostly stop .. Thirdly I found the ride hard vs the softer lower feel that the Cadenza has ,Granted I liked the HUD screen and the comfort I would never go back to the K900 again
I suspect if you take road trips the K900 would be more comfortable but not that much noticeably different .In Canada, I had the V6 which was not available until this year in the USA I can only imagine the gas it would use
good luck