I've never done a puff quilt, so have no idea how the construction of that will relate to the one time I used Minkey. I've only used it to back a flannel pieced quilt.
The two things I noticed about Minkey is that A) it stretches a lot and B) the reverse side is slippery. To handle both the stretching and the slippery issue I used basting spray to baste my quilt, and a walking foot to quilt it (I did do some FMQ around some of the appliqué - but the bulk of the quilt was SITD with a walking foot).
Spray basting helped tame the slipperiness of the reverse side of the minkey. Without every square inch of the quilt basted together by spray, any unabated area wants to "walk" away from the quilt top while quilting - even with a walking foot. It just slides around and you get puckers, puckers, puckers!!!
I did prewash my Minkey, not for the shrinkage issue (I don't know if it shrinks), but for the "fuzz" issue. Like flannel, the first wash and dry will create a good amount of fuzz.
Hope this helps.