Double it and you might have a chance, but you're right, a hasty repel is a scary idea. I've broken paracord with a lot less than 550 pounds, at the knot.

For the bulk, 1" tubular webbing might be easier to handle and is certainly a LOT stronger.
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-IronRaven

When a man dare not speak without malice for fear of giving insult, that is when truth starts to die. Truth is the truest freedom.