I have a C.S. Johnson Grab 'n Go Hook which solves the same problem (for moorings) with a different approach. They each have their pros and cons when you compare the two approaches. If I didn't have either I might get the Hook & Moor, because it can be used with any dock line. The Grab 'n Go has the advantage of being metal so it won't chafe on a mooring ring but it's not secure enough for leaving the boat overnight or away, and it's SWL is only 700 pounds so you'd still want to replace it with a more secure setup once you get settled on a mooring. Hook & Moor can also be used for dock lines.

One other note is that if you loop a line through something you should always tie both ends back to the same cleat, so it doesn't chafe through by a sawing motion as the boat moves. It should never be left with a line going from one cleat through a loop (or eye) then to another cleat.