The first pieced quilts I made were flannel and I used that really fluffy Fairfield. I think I even used two layers in one of them!
I had no one around to tell me that it was too difficult for a beginner, so I didn't know any better. I was also quilting on a machine that wasn't very well suited to free-motion quilting, so I was a mess, start to finish! :)
The quilts were slippery and difficult to manage, but not difficult enough that I gave up quilting. And they came out really cute and have been dragged around and laundered a lot for the last 3 or 4 years, so they're holding up.
If I had known, I would have used someone else's suggestion and pinned the bejeebers out of it. :)