With all the throw pillows I have been making lately, I do like two battings, but can't imagine doing it in a larger size honestly. And I have a HQSS16 sitdown. I love the definition of the quilting, but they are heavy when they are quilted. I just can't imagine that in a full/queen/king sized quilt.
It was a bit harder to move through the machine too.
I think if you want fluffier, you might consider the type of batting and how far apart you are quilting. The more you quilt, the denser the sandwich gets and you just get heaviness vs fluffiness...