Although most quilters think of Aurifil cotton, Aurifil also shows a poly thread for longarms on their web site. That is probably what Dee was referring to.
I use a lot of MetroEmb thread, because I like the sheen on most quilts. However, if you want a matte finish, Connecting Threads has poly cones meant for longarm sewing. I have used CT cotton, but I really prefer the poly threads in the longarm. I purchased several sets of the CT cotton spools years ago when they were on sale, and I hope I'll eventually use them. For piecing I've turned to mostly BottomLine.