Great, glad to hear you got it fixed. FWIW either material should last indefinitely. The two main advantages of using a harder material like PEEK are:
1. Easier to knock the valve open. Allows using less hammer spring tension and/or a lightweight hammer. This arrangement is advantageous for better efficiency, quieter report, and a generally more pleasant shot cycle.
2. Better compressive strength allows a relatively small sealing margin. That is, you can go with a smaller diameter poppet which is advantageous to flow rate, whereas a "lesser" material would extrude and fail. In the link above I stepped through an example with calculations.