Have used knots for all the halyards for more than 10,000 miles of sailing. For Dacron, used a bowline. For the modern ropes, have switched to a buntline hitch. Did a TransPac with a Dyneema cored main halyard with a buntline hitch to secure it. No problems.
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If the cringe on the sail is big enough, loop the halyard through twice. No shackle allows you to easily end for end the halyard to even out UV damage if you have internal halyards. You can also cut off a few inches of the halyard anytime you feel like it to change the wear points. Ditched all the shackles after a main halyard shackle drew blood 40 years ago. Avctually still have shackles on the spinnaker sheets as that is a place blowing the sheet/guy has some benefit. Strength is not an issue unless you are ultra small diameter line as a big enough to be easy to hand is probably 10 times stronger than it needs to be.