I ride hard and have had a pair of Mike Nicks and am currently riding 1260. Both have been bombproof and I have put them through everything skis shouldn't go through. My friend has chronics and they have held solid.
The biggest advantage of the pivot compared to the px is that the pivot would not slide back and release when landing switch, like a standard track binding does. The increases forward pressure on the px addresses this to some degree, but will still slide back under hard impact.
The px releases...
the reason I say this is because those invaders have issues and the rossi's are ok at best. The chronic can be buttered easily if you are strong or over 155 lbs.
counter is "natural" for most people. Right side spins are harder for most. This is most common for right handed people because we drive ourselves left with our right arm and shoulder.