A picture is worth a thousand words:
Cleat: Holt CL217MK1AN Starbord entry cleat.
Block: Ronstan RF20101Single block.
The white rope with red spiral band is the Dyneema halyard.
I OXO it off on the horn cleat as an insurance just in case the teeth of the clam-cleat get blunt one day and slip.
What if you need to take the sail down real quick? I think it is a safety feature to have the halyard in the clamcleat only. All it takes is one little tug and the sail comes down. And if you dont trust the cleat, why bother using it? When used with the the right sort of rope it will hold well. The horns won’t get blunt (they already are), it will hold the halyard for decades, unless you try to cleat steel wire in it that is.