The 5 materials I started with are: Nylon 6/6 natural; Black Nylon 6/6; Zytel ST801 (heat stabalized, impact modified nylon); HDPE; and of course UHMW (in a beautiful Kelly Green).
Tommy's (the guy I made these for) saddles split right at the base of the radius.
I'm going to bet on the Black Nylon, but the UHMW might do well.
The nylon also has a higher constant use temp. 212F compare to 160 for UHMW & 180 for Acetal.