I bought a 4520 this fall. Had a 4700 that was 12 years old. Wish I could have kept the old horse instead of trading it in; it was a great tractor. I like the new unit, which has many new and improved features. But a couple of issues:
1. The rear R-4's were changed from 7.5-24 size to 6.9-24. Why? And the rims were downgraded from 8 position widths to 2; the new ones are simple deep-dishes that are too narrow in the default position and too wide in the rotated position.
2. the 4520 came with a rear hydraulic hookup that was not optional. I didn't need and didn't want. And the plumbing for it is really thrown on -- big pipes wrapping around the back of the tractor, big boxy module for the hydraulic bleed valve and filler cap. Of course I had to go out and buy an attachment to use the hydraulics -- a back blade. And that has its own issue -- you can't turn the blade around to push backward on snow, etc. Cheez...
3. The e-throttle, which makes the foot pedal work like an auto -- depress it more, the unit speeds up. Well, it's kinda nice, maybe handy for FEL work, but if you have to drive somewhere over moderately rough ground, you're in for a herky-jerky ride, because the throttle is overly touchy.
jim