I often use mono as my bobbin thread when doing wall hangings or table runners etc. It is really helpful when doing fmq and having a lot of color changes in the top thread. It takes some getting-used-to and you have to adjust the bobbin tension a bit. You also might need to fiddle with the bobbin winder you use -- some wind very tight and it causes the mono to break. It took me awhile to get up the courage to try it in the bobbin but it's been a real time-saver for me and also makes the appearance of the back of these small pieces more "uniform". I doubt I'd use it for a bed quilt or anything you'd want to "cuddle" with -- or for a kid's quilt, however.