Funny story, every binding you just mentioned is also mostly plastic....the only binding up there that isn't plastic is the FKS, but you have to get your hands on some old 155s. Also, please note what most pros use for bindings (I know it's sounds like I'm trying to say get what the pros have, but I'm not - they just trash their stuff more than anyone), pretty much every pro without a binding sponsor is rocking FKS 180s or STH 16s, there are a couple rocking Jesters, but I've never seen a pro riding PXs and for good reason.
That's sick that the STHs work out cheaper, cause they're a great binding and that's my personal recommendation. But, ultimately, it's up to you and what you're feeling - don't just buy a binding cause someone on NS says too (that includes me), you need to get what's right for you so you can enjoy them and be safe. If you feel like the PX12s will suit your needs better, then go for them, if not, get the STHs or something else, you just kinda gotta feel it.