Quilting on minky fabric with polyester batting.
Minky part on front was only some blocks, not all over, but backing was whole minky fabric which is stretchy and thick. Usually, if batting was cotton 100%, it holds a top and backing together at least some degree, but polyester. This quilt sandwich was totally fluffy which didn't cooperate with me for quilting.
Back.
I think that using minky fabric for only backing is not that hard to quilt - it was heavy even with polyester batting, though. But, when I go through quilting on minky parts on front, I somehow slighly lose control of my sewing machine and get confuse because I cannot see the stitches. I broke 3 sewing needles on minky fabric for this quilt.
It was a good experience for me. I felt better when I finished quilting this quilt :) and decided to charge extra next time :-p