I'm on the 4th year on our second JD 946 with rubber rolls. 

Our main reason for going with JD in the first place was dealer support, second was the cutter bar design.  IMO, there's no better cutterbar than on the JD, heavy built modules (segments which are comprised of cast housing, 3 big gears, shear hub, and cutting disk), which can be removed individually if damaged without taking the entire cutterbar apart (btdt after hooking into a big f'ing rock, and the only substantial damage was a dent in the housing, 2 sheared hubs, and lots of broken blades, complete repair parts bill just under $400). 

Be prepared for using at least 120 hp with sharp blades on 13' cut in rolling ground in mixed grass, and you'll wish for more if you're inclined to run with dull blades.

If you've got a 3rd hyd remote on your tractor, definitely opt for the hyd angle adjustment on the cutterbar on any center pivot due to how far behind the drawbar the cutterbar is when going over humps, unless you have extremely flat ground, then perhaps you can get by without it.