I use CT polyester thread a lot because I don't have to fill the bobbin as often and my FMQ (which is far from perfect) does not show up as much. It is not as high quality as some of the more expensive threads but I do not do quilts for shows ..my quilts are practical and I use fabric that I get on sale. It still makes a nice warm quilt even if not perfect. I have not had tension problems because of the thread. I did recently have a tension problem because my backing was a different weight fabric than the front..it was heavier...and I found my thread pulled up from the back and could not get the tension right on FMQ...lesson learned...use similar weight fabric for front and back.