I don't have any luck with the poly in my bobbin either. my Bernina just isn't a happy camper. Been kind of afraid to try it on my other machines.

Superior usually has the needle size on the label, doesn't it? I'm pretty sure mine does. I'm thinking its 90/10.

I love Superiors monopoly invisible thread. Use a ( thread net) I always put a neutral thread ( or one that matches the backing) in the bobbin, cotton if using my domestic machine, poly if using the Longarm. The thread spool/ cone from superior actually tells you hat needle to use. I've never had problems with shredding, breaking or any other issues. I use it often to stitch out multi colored appliqués .

I have used the monopoly in my bobbin with no problems. Some of my quilting friends swear it does't work. You can just try it and see what happens. Look i=on superior thread website and see what they suggest and they do your own thing. I always say there are no rules in quilting. No quilt police. Try anything.

You say your background is light beige and your books are jewel tone. I would use clear thread on the beige and the black on the jewel tones. I always use light weight bobbin thread when I sew with monopoly.