I picked up the XG850 this spring and really like it. I wanted the 520 but was told it had a 2-3 month wait list. The XG850 was still in the crate and I got a great deal on it.
PROS:
1. fast
2. smooth - no problems in tilled fields or handling bumps
3. lots of pulling power
4. I like the metal dump box, front and rear hitch receivers, Takes a big load and manually dumps easily by hand
5. electric steering is the cats meow
6. low center of gravity makes the machine feel very stable.
CONS:
1. twitchy throttle takes a while to get used to
2. drinks gas like there's no tomorrow
3. expensive accessories i.e. wiring harness, roof, lights, windshield
4. wants to go fast - hard to go slow even in low gear i.e. pulling lawn roller
5. turning radius - could be better, I'd like to see under 10'
6. The dump box bed height seems a little on the high side if you are loading heavy items, but great work bench for servicing chain saw etc.