I converted from wire/rope to all rope using stayset X. The increase in stretch is noticeable and requrires resetting the main after little sailing. If your halyards lead aft to the cockpit this is no big deal but a little pain if singlehanding and you have to go forward to the mast. If I were doing it again I would look at one of the aramid lines even though the smaller diameter can be hard on the hands. You get less stretch (very similar to wire/rope combo) and lighter weight. More money though.
Let us know how you proceed.