I generally use the 50 weight for both piecing and quilting. The big difference is the color. For me piecing uses neutrals and quilting uses color. While I do agree that Connecting Thread is a bit linty, my machine likes it and I usually get it on sale) For variegated quilting thread I get Star thread which is produced by Coats and Clark. We did use assorted weights in the quilting class - but my thread stash is huge and before I invest in different threads (unless it is for a special project) I use what I have.