If I'm moving plants within the garden rather than mailing them to someone, I just dig up the clump, divide it if necessary, and then replant with as much soil still on the roots as possible (cut back the foliage too if it has grown enough to wilt). If I'm mailing them then they have to be barerooted and washed, but it adds another level of stress to the plant by potentially damaging more roots than if they're moved with soil.
I agree that I wouldn't be moving them at this time of year in a cold winter climate.
