Last month, I bought one of Tristans special variegated bundles of thread. It is smooth and sews very nice. I have the 28 wt and the 40 wt in my bundle.
Although, there are a couple of the spools that I'm going to have to really work hard to use. I do prefer the new syle of variegated threads that has a much shorter distance between changes in color.
I blogged about it here, and you can see what I mean by the color changes in a sample I did when trying out my purchases.
http://quilt-knit-run-sew.blogspot.c...r-threads.html
I did buy one of the "Piecing" bundles and it consists of 6 50 wt threads. I really like that one for piecing.