The Nyalic will bring back the shine & have your decks / whole boat shining like new.
It is magic stuff!
On application the Nyalic has the consistency of water almost, I have applied it with a fine brush & I have found it is better to apply it with a sponge.
I have not used it on a rib deck but where I have used it on topsides & cabins I have not found it to make the area any more slippery that it was pre application. It doesnt leave the treated area slippery as it would be after an application of wax for instance. As for adding grit, I have never tried it but I dont think it would work as Nyalic isnt very sticky / tacky & I cant see it holding grit, though the supplier in Vic. might be better able to advise you.
The product is expensive I was told though I wasnt paying for it myself!
You will find that a little goes a long way & a litre would probably be enough to coat your boat several times.