I used original Dual Duty for decades, it was a cotton wrapped poly. Way back when the quilt police were concerned that the poly would cut through the cotton, but I don't seem to have that happen and times have changed. Poly threads have significantly changed since the 70s! Never noticed any thread shrinkage issues, but I tend to only lightly quilt and not do the heavy quilted currently favored.
About 10 years ago now, I started using my friend's long arm which could not wind a decent bobbin to save our quilting lives and sanity. Started buying prewound M bobbins from Superior Threads, could find L locally but not so much M... Started using So Fine! and now pretty much use it all the time, top thread, bottom thread, both piecing and quilting. But then I won an auction and got a huge lot (basically if I don't care about color I have a lifetime supply) for next to nothing. It worked well in my ex-machine "Cranky Bernie" the Bernina, it works in my vintage machines. Edit: Forgot to say using it right now in my semi-industrial (fast) straight stitch Juki.
BTW, Superior Threads has a Labor Day sale going on! (best sales link on home page, not so fine page)
https://www.superiorthreads.com/thre...-fine-50/c/116