Open cleat

It only needs to ratchet one way - you just take a couple
of turns in the right direction and pull.... When you tack
just let it go and wrap the new sheet in the same
direction.

I believe it was Paul Elvstrom who invented the cam cleat and he used it in the 1948 Olympics sailing the single handed dinghy which was the Firefly.  He was the only competitor to use them for the jib sheet and he used a "horn cleat" for the main.  Perhaps that's why he won or was it because he was the only sailor to sit over the side of the boat and use toe straps?  Doubtless the other competitors sat upright in flannel trousers and a blazer, possibly with a straw hat called a "boater".  He was a cad!

we have horn cleats on our 1/4 tonner for the jib sheets, works fine and is probably faster than cam cleats! enough turns on the winch and you can lock them off with a single wrap round the cleats.  If we needed too we would have changed to cam cleats by now, for a dinghy cam cleats will be easier and for a few quid on ebay you can pick up a couple of decent ones so why not change?