Replying to 3 cheap bindings- which ones best?

I was poking around on evo and their outlet has 3 bindings in the 150$-165$ range. 

px 12 series (do the look/ dynastar ones differ at all?)
 
Rossignol Freeski2 120
 
salomon z12 ti
 
 
 
and whats up with the boner heelpieces? are they really necessary?