I am never happy when I use the pillowcase method for a quilt. I can never get it as flat as when I do a regular binding. I am thinking the minky will stretch using the pillowcase method? If you were just going to tie or do bar tacks with the pillowcase method, it should be okay but I wouldn't want to quilt it with the pillowcase method. I have not done a minky backing though so this is just speculation on my part.