I use the grey, i don't have any experience with the white. In my experience, if applied in a thin coat, it doesn't shrink. I use it for final bodywork to fill tiny imperfections or smooth a joint. It feathers pretty easily, but kicks within a few seconds, making it tough to spread. So apply tiny amounts and work quickly. It sands well. But if applied too thick it will shrink, so if you must use it to fill something like a door line or deeper, expect to apply a couple coats.
as always, your experiences may vary.