Mixed feelings. They can be a pain when raising the main and can be handy when sailing shorthanded.
On our Sigma 33 with a loose luff (meaning the sail does not stay attached to the mast when lowering) you couldn't do without them when sailing singlehanded.
I made my own system with some lines and simple clamps so I could pull the lines along mast and boom so they didn't interfere with the main while hoisting it. I simply put them in place just before lowering the main (short trip to the mast required) and stowed them again after I flaked the sail to keep it on the boom for storing under its cover.
I hate the systems you find on most charter boats; no matter what you try the battens always get in the lines of the lazy jacks.
Last edited by sigmasailor; 08-18-2009 at 12:21 PM.