We use medium jumbo white brass frets on our carbon fiber guitars. We chose this material over stainless steel because it helps the guitar have a softer tone. Our fretboard is all carbon fiber.
You can re-fret our guitars, but the process is a bit more involved because you must use epoxy resin and a jig to press and hold the frets in place. If needed we have clear instructions for this that have been used by a few luthiers already.