Tried it. Nothing alive falls through doors now if they were standing on them when the door opens.  On the plus side, critters will still fall through open doors if they're already falling. The trick is to get them falling in the first place...  Oh, and eggs still act the same way they always have so just change your kill rooms to drop extra eggs into water through a door and drown the critters when they hatch. Much simpler automation and not difficult to change where eggs are delivered using the critter sensors.