I have used it before. My kids love how warm it is. I'm not a pre-washer and I've made them with and without batting. I live in WI and it gets cold here. I used batting with the minkee. If you are in a warmer state, I would probably skip the batting and maybe put a layer or flannel if you needed something in there.
On a longarm, it does work wonderfully. I've sewn it on a domestic machine and it's hard to keep it from sliding around. Your longarmer should not have a problem with it but do talk to them first. Everyone is different and they might have special instructions.