I am on my third serger which is a Babylock Imagine with air threading. Love it! The previous one was a 5 thread machine Pfaff coverlock....loved it. But I no longer make clothes as much as I used to, so I gave it to my DIL. I use my serger for piecing the backings, flatlocking pieces of batting together,finishing off the edges when I cut up old white t-shirts for dish/dusting cloths, etc. I did use it in piecing a quilt once, and yes, serging can add bulk to the seams. I may try it on a flannel project and see what happens.