I almost pulled the trigger on the PX12 jib before I bought a set of PX14 TI bindings.
The only thing that turned me off to the PX12 jib was the composite heal. It is plenty strong believe me. I've been riding on a set of SAS2 100s (essentially the same thing, but lower DIN range) all last season with zero problems.
Performed very well. Heald on tight and always releases when needed. Had a little bit of a problem double ejecting in pow here and there when it got sticky, but mainly because the skis I was using at the time loved to dive. It took quite a bit of effort keeping those tips floating.
Out of those three choices, I'de recommend the PX12 over the NX12 because the PX12 has the axial heel which provides elastic travel. Essentially, if you stomp a sketchy landing, the heal will give/travel quite a bit before releasing. This gives you time to recover before your skis go flying off. IDK if you're familiar with that type of binding, but it's one of my favorite features and the reason I like to stick with the axial heel pieces.
As for the squire, I have no first hand expereince with marker nor do I know much about them so hopefully someone else will chime in.
Brian suggested these and the squires to me. talk to him about the px's, but he told me they would break.