@Toodles,
I would not recommend the Burtons or any binding using micro disks due to the amount of baseplate flex in the bindings...if you like soft, then ok, but if you want medium to stiff bindings, stay away from all of the above.
With that said, if you want super stiff, I would highly recommend Flux XV or medium-stiff Flux XF. Also Drake (if you can find them) Podium or Radar are really good too...on the Union side I would say Forged Force (super stiff), Force (medium) and Atlas (Medium-stiff)...I like the feel and position of the ankle strap on the Atlas better than the force, but the Atlas highback is a little on the soft side for me.
Hope that helps...