OP, your poll is a little flawed, since the Guardian and the Tracker are the exact same binding with a different color scheme and name on the side. Blister Gear has a review of them.
That said, I have the Guardian on my Codys. It's a burly binding and is just about as solid as a regular alpine binding. If the snow is the least bit soft, you can't tell the difference between this and a regular binding. If conditions are hard, there is a teeny-tiny amount of play, but it's almost imperceptible. They have a much lower height than the Dukes.
It detaches into walk mode easily by pushing back on the lever with the tip of your ski pole. Getting the heel riser up with just your pole is kind of a be-yotch, though,
especially with snow wedged into the mechanism.
All in all, I like 'em.