I personally do not like Dutch doors....... They have a tendency to become misadjusted, not maintained, and always seem to shut (the top portion) thus making somebody do the limbo to get under the door...........
Not hard to do when wearing regular clothing... but (showing my age now) when wearing bunker gear. a thirty pound air pack, and carrying radio, forcible tools, and a flashlight - it is extremely hard to do the limbo when not expected in smokey conditions. (PS did I add that I am a 6 footer and weighed almost 200 lbs - fighting weight days of yesteryear)