I'm running EZ on an MT-845. Although I'm just using the EZ-Guide+ to control the EZ-Steer, I have changed and tweaked things until it is as smooth as silk. It is to the point that the weak link in the chain is the GPS signal itself. Tractor is seldom more than 2 inches from where EZ tells it where it should be.

This post shows one of the places I tried mounting the antenna and also the current and last place I will try it.

http://talk.newagtalk.com/forums/thread-view.asp?tid=18901&posts=8#M129204

I am now very satisfied with where the antenna is. I had previously tried to keep it as low as possible, but since adding the T2 to my EZ-Steer, the antenna height no longer affects accuracy and I can put it as high as it needs to be to see the maximum number of birds.

I believe the 500 would be even smoother on curved guidance, as the unit updates EZ much more frequently.