I honestly love my EXs (minus the problems everybody has with their ratchets).
I don't care too much about aluminum vs. plastic but I do, very much, like the "wedgie" canting that Ride bindings have.
Is the Burton (Cartels or Malavitas) "auto cant" similar to the Ride "wedgies"? The canting definitely made a difference in my comfort last season.
I've ridden the Ride SPIs which had the 2.5 canting (less than half a season if anyone wants to buy 'em) but found them too responsive for my not-terribly-great skill level.
I think the sweet spot in terms of responsiveness would be between the EX and the SPIs.
Any thoughts in that regard?