I tried potato starch for the first time when I made a pot roast 2 weeks ago. DH thought the gravy was made with flour and pronounced it amazing. It was incredibly easy to use and at least 2x as effective at thickening as flour. I pulled a ladle full of the juices from the crock pot and let it cool in a bowl to barely warm. I whisked in about 3T of potato starch and then whisked part of that into the juices in the pot. I was really surprised how little starch thickened it up and I had at least 4 cups of thick, smooth gravy. I don't think you can make a roux with it, so it might not always be a perfect substitute for flour, but for making gravy for a crock pot dish, I think it beats flour, hands down.
CW-125, part calorie counting, part transition to primal
GW- Goals are no longer weight-related