A good plastic binding is honestly no weaker than metal. At the same pressure you'll crack it you'll bend aluminum. Either way your screwed.
Flow NX2's. Canting, full aluminum. It's really either that or Rome. Union isn't canting anything till next year and the only metal part is the heelcup. Majority of the frame is nylon.
Go ahead, drink that kool-aid.
FS: Forum Sauce 142 $200 plus shipping
FS: Flux SE30 $75 plus shipping