Compared to the basic plastic the ultrium jokeri is appreciably more overstable, which makes it a fantastic counterpart. You can hammer this forehand into a headwind and back it to fade out still. It has the torque resistance of the zone whilst having a less aggressive, more putter like fade, which gives me confidence using it over a greater range of distances.
The ultrium plastic is like a stiff, glossy star plastic. I think for most situations this will be my preferred plastic for this disc as the stiffness helps me get a cleaner release.