This from the Service & MX Manual for the Aerocet 3500 Amphibs...
First, waxing is usually not an act of creating a slippery surface (polishing is
). Waxing is to seal the paint against environmental effects and to make it less prune to allow for chemical reactions to cause corrosion. Polishing reduces drag, waxing keeps it so...simply by helping to avoid contamination to stick. On glass we use RainEx, which bonds with and seals the glass by filling minute holes in it.
Corrosion is a non issue on Aerocet floats, rivets causing large amounts of drag on conventional floats are missing.
I think the difference in material, smoother surface and already improved "slipperiness" of the float makes waxing largely unnecessary on most composites. Unless the wax serves some purpose of protecting against UV and aging, it is largely unimportant and serves no purpose other than to improve looks (a matter of finish, not anything else). Not for no reason are there nano waxes which actually reduce the drag coefficient of painted metal.
I can imagine a composite material becoming "too slippery" if properly waxed. Wax is basically a barrier between the surface and whichever medium attacks it, thereby avoiding contact with the water (hydrophobia). This contact to the water is, in turn, what allows us to have any control at all.
I would generally be careful with applying any surface treatment to a composite material, just for fear of chemical bonding and risk of discoloration. Glider pilots are ANAL about using soft soap and lukewarm water to get bugs off their wings. Soak & Wash. More than once if needed. Then leather dry to avoid water drops to dry, which in turn cause drag.
Unfortunately most water has discoloring character on every surface, so I'd rather clean more often, than wrong once.