I'd question the PVC. Not just because of how slick it is but it transmits heat so well. It could lead to frostbite on the feet. Metal would also be a concern.
Thanks, I figured the link out finally. I'm not expecting all the materials to be ideal, and in southern Georgia frost bite isn't a major factor. Some material will be in the test for potential elimination. I figured they would avoid certain material but surprises happen.