My Note 4 is around 7 months old and I updated to Lollipop 5.01 while I was setting the phone up for first use, so I never really tried kitkat out on it. As I was waiting for the 5.1.1 version of lollipop, I decided to revert to Kitkat (via Odin)just to see if there was any difference in performance/battery life etc.. and there wasn't, in fact I preferred lollipop so I re-installed it and the it updated OTA to 5.1.1
No issues here, although I do find with alot of intense usage it's hard on the battery (what phone isn't? ) so I bought another battery, simple!
Enjoy the phone
Merry Christmas ☺