I used a bamboo batting in a lap quilt recently. It was lovely to work with, the final product, heavily free motion quilted, had a lovely drape, was lightweight, but warm. I really liked it, but will not use it often, mostly because of the cost.
I read recently that the toxic processing has been improved upon to be significantly more green. If the reports of increases in cotton prices are true, it may be that bamboo becomes a strong alternative.
RST