I recall reading somewhere that people who get their feet swept out from under them by running water often lose their shoes and pants from the current. Or their shirts, if they are going down river head first.

I might not be remembering correctly, or it might just be a myth, but neck carry might stay with you when pocket carry doesn't.

And if you need to actually improvise a floatation device from your pants al a old timey WWII manuals, will you be able to empty your pockets in time?

Keep your pants. Stay out of the water.