"Always use good thread" is my motto. The last time I used cheap stuff was a mistake. I agreed to quilt a friend's quilt on the proviso that she bought the cotton...it kept breaking. I assumed that she would get good stuff because she is a seamstress.
However, I have plenty of Coate's stuff and it is fine. Unless the quality has gone down a lot lately, it sounds like it may have been a bit thick for the tension discs on your particular machine?