I originally bought a Polaris rzr 800 4 seater new in 2010 and recently sold it. It had over 4500 miles and wad 5 1/2 years old. So here goes the comparison. I’m the proud owner of a 2015 Polaris rzr 900 4 seater. Bought full glass window and aluminum roof. First ride went 62 miles and this is what I noticed.

Pros- it’s has incredible speed over the 800, did not max out on first ride.
Shocks are stiff. Fix adjust 20 clicks out much softer now.
Seats are great, good support for back and they soak up the small rocks.
Engine sound is awesome
Full windshield allows full view..which is a plus.
Power steering is excellent.. can be a little squirrelly as u have twice as much power over the 800 4 seater 75 hp. Just ease on the gas.
Cornering was great. Rear A-Arm held it steady even when doing donuts in the dirt.
Ground clearance is great never hit a rock yet..lol
You never feel that it’s going to tip. Due to factory sway bar.
Love the deep glove box.

Cons- front differential makes noise. Apparently there has been some good fixes to this on forum. Thicker oil and 2 washer under rear of front diff. Have yet to try this.
Air cleaner change. Pits cause u have to remove stock box each time u check or change air cleaner.
Shifter into gears– you have to make sure it’s in gear. There is shift slack and the instrument says it’s in drive but it’s actually in between gears. This may be me ad I’m just getting use to it. No noted problems just make sure it’s in gear before u floor it.

Bottom line is it is the best machine I’ve driven. It handles better than the 2 seater 1000. And it is perfect for tighter trails and roads. I say buy it over the 1000 4 seater cause the 1000 is too long and it would not fit on my trailer. Hope this help new buyers out. Buy the 4 seater Rzr 900 . You will be very happy with it!!!