Sphugmum moss tends to help prevent mold forming on eggs but other than that I don't think there is any difference between the two for egg laying. I have read that coir or coconut husk can cause eggs to go bad, unless the bed a beast stuff is different from other forms of coconut fiber as I have heard several people who successfully incubate eggs in coconut fiber.
Other egg laying mediums is plain untreated potting soil, straight or mixed with vermiculite with sufficient water added to ensure it clumps nicely, or just vermiculite as well. Though vermiculite can be injested and cause problems in adults and babies both, better to stick to either a mix, straight soil, the fiber (though this can also be injested as well and cause blockages) or the sphugnum moss. Experiment with all choices till you find one that works best for you.
-----
PHLdyPayne