Thanks so much for the helpful replies. i do have some polyester, although it's not bottom line, and I was just eyeing the Aurifil speculatively today at KQ. I wish now that I'd bought some.
Thanks, also, for the feedback about the shop owner. She has just won a dealer award from a major machine mfg and is known for customer support, so I reluctant to just discard her response, particularly given how vehement it was.
Hugs,
charlotte