On my Hunter 37C I repainted the non skid with Interlux one part poly, flattening agent and added non skid powder from Interlux. I experimented with primed and non-primed areas. I found no difference in coverage or durability. The non skid that I repainted looked like yours. I cleaned it first to be sure there was no wax or residue, taped it off with Fine Line tape, mixed paint, flattening agent and non skid and rolled with a 4" foam roller. Keep the paint agitated as the non skid wants to settle out. I also experimented with how much non skid to add to each mix. The more flattening agent added the thinner the paint goes on, experiment.
On my very worn out cockpit floor I used Sherman Williams polyurethane (?) house paint and got a perfect color match that has held up over two years. My bad was not using enough sprinkled on non skid grit which resulted in a non uniform appearance. Boat Works Today has a great video using Soft Sand sprinkle on non skid.
Thanks Allen for sharing your experience and observations. Did you consider just paint without nonskid as I read somewhere that the paint is so thin that the original texture will come through unless worn. Second, did the flatening agent change the color and what ratio? Would the grit alone flatten the color?
Lastly, how easily can you judge that the in the can nonskid grit is staying uniform while applying?