My Kumho KW-11's, my brother's Nordic IceTrac and my dad's Nordic WinterTrac have no problems in the rain. My wife's Blizzak WS-50s leave something to be desired, though. The majority of winter tires should be fine in the rain, though some aren't all great.
If you can get your winters on your car in very short order on a moment's notice, and if your all seasons are good in the rain, then keep them on the car for now. Otherwise, get those winters on while there's no stampede to do so.