I just got a couple of the 200 thread count ones to use for backing. As soon as I finish piecing the top I'll let you know how it works for me.
It may be awhile as I am also hand piecing and still have a few left to add...over 1200 of the 2-1/2" squares in place and only about 300 more remaining. Got a bunch done this weekend, so maybe this last bit will go pretty fast.