Have you checked your intake boots? Mine started leaking around 2500 miles on my 900. At about the same miles on my current 1000. Id hate to see your guys excellent runners go down because of dust getting sucked in your boots. Its a very common problem.I have a 2014 Ranger XP900 with over 14,000 miles on it and still runs great. This past fall I got tired of all the rattling as I was driving so replaced all 4 half shafts and wheel bearings. What a diference it made, sounds like a new machine. That also eliminated a slight delay of what felt like going into gear. That was the slop in the cv joints (part of the half shafts). I don't intend doing anything with the engine as long as it keeps running.
You are right on maintenance, but that's easy to do. I think listening to your buggy is important. Mine started having strange noises in the rear and after a little checking I found the RR cv joint had some wear. I figured if one had wear the rest were ready to go so changed all 4 half shafts. I have been so impresed with the 2014 Ranger (with14K miles) that I ordered a new Northstar ultmate. Hope that it will arrive by late April when I return to Mn from AZ.I think they would last a very long time depending on how well maintenance is done.