In my experience, special meals have never been anything but trouble. While I have never ordered one myself, on almost every flight with a meal, I see the flight attendants struggling to get special meals to folks and there is always one missing or incorrectly ordered/fulfilled. And (WARNING- I am about to make an overbroad statement) the folks who are ordering the special meals are OBNOXIOUS if it is not right. Look, if you're not on an international flight, the longest you will be on an airlpane is about six hours. So unless I am upgraded, I'm not eating the airline food anyway (it has always been amazing to me what people will eat just because its "free"). As for special dietary needs, my father (a diabetic semi-frequent flier) always packs a snack for himself when he flies.