There are a lot of mixed feelings about microspun around here. I don't think anybody would disagree that it is supah soft because it is. But it is also VERY splitty and can be generally funky to work with. The plies are pretty defined so it is really easy to split the yarn. The softness makes it pretty slippery too. So a sharp needle that has some grip is probably the best way to work with it (from my experience anyway.) I am not a fan of it but i have been sucked in by its super softness. Someone has knit washclothes out of it and says they are WONDERFUL.
haven't used the other though.