I did have a cone of 40 weight Aurifil I tried using on my APQS Lucey when I first got it. I did have some thread breakage with it and when I switched to OMNI that stopped. I haven't tried the Aurifil thread again as it is a bright grass green and I haven't needed that color. It perhaps would work better now that I have more experience on my long arm and seldom have thread breakage with SoFine. I have a queen-sized flannel quilt loaded and I am going to use OMNI as the top thread and SoFine as the bobbin thread. I haven't used this combo for a while but suspect it will just go fine. I may have to loosening my top tension as the OMNI is 40 weight. Actually, I have already loosened it about a half turn as I just checked the feel of pulling the thread through the needle and it seemed to pull a bit harder. LOL, now I will just have to stitch something out and checked how good my "Guess" was.