If you are thinking about using a shackle on a halyard or jib have your wife swing a shackle at you for a few minutes to see how it feels to get whacked by one. Not sure how manufactures talked cruisers into shackles but I'm guessing the racers wanted then for fast change outs. Ain't nothing done fast on our boat when offshore and I NEVER want to get hit in the head by a sail swinging a line with a shackle attached! And since we don't use them I won't.

My 2 cents.