I have and use both the lift and boom vang. When the mainsail is up, I pull the topping lift off the back of the boom and use the sail to hold the boom and the adjustable vang for support also. When I put the sail away, I pull the topping lift line off the cleat on the mast and put it back on the ass end of the boom and put the load on the lift.
I hadn't thought about making use of it to help out in light winds like Sailingdog mentioned, but the next time that condition exists, I will give it a try and see how that works, good idea, thanks Dog

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When I get run up the mast in the chair, I use the topping lift line as my back up safety line attached to my harness. Then I use the Spinnaker Halyard for the chair and the the Head Sail Halyard as my primary harness safety line. Someone told me that I was going with a little overkill, but from top the mast, the deck looks a long ways off and really hard :cry: and I don't think I bounce too well.