Like practicaly every other 737 driver I deselect SPEED mode at some stage during the approach in good wx or light rain and leave the AT on (or off completley if maintaining raw data skills). But I do leave SPEED in all the way down to the deck in very heavy rain especialy during approaches at night onto short strips. It actualy does help back up your flare judgement when Natures throwing thick buckets of water and lightning in your face.