I like Thousands of Bolts and have purchased fabrics from them. The features you mention are definitely useful.
You could say that I am a fan - sort of. Their site frustrates me because I can see at most 36 fabrics on one screen, and their filter/sort really stinks. i hate flipping through 30+ pages to find a fabric, so frequently I just don't shop there!
Maybe their next improvement will fix what i don't like about their site!