Rodney, sadly, the reality of being in a war refugee situation really makes the question totally moot. While not getting into the details or sources, these I have heard first hand.
When you are a refugee you are fighting rats and other scavengers for food, as well as of course the soldiers, who themselves are getting somewhat desperate for food, which is growing increasingly scarce as the conflict breaks up standard food production / distribution channels. If you are a mother you are trying to avoid getting your daughter raped, or killed, and you are praying your sick children do not die of some disease you wouldn't expect to get in non war time. That's before they die, after, you just carry the sadness and loss, and maybe a few possessions you might be lucky enough to hold onto through the nights of sleeping in fields and empty farms etc. There are no nice neat stories, and no neat packing methods that will cover a soldier, or just a plain thug, or both, taking everything from you and leaving you lucky to be alive. So forget that notion of planning for something you can't plan for if you are talking about the real world and real war refugees. Basically you really do not want to be a true war refugee, get out before it gets to that point if you can, that's the only real meaningful planning you can do.
For disasters, varies so much country to country it's almost meaningless. If I look just here, what I want to have, and have, is a good, efficient, white gas stove, msr, with a fair amount of fuel, a gallon at least, and the neat tricks I've learned here about cozy cooking and so on. And a decent amount of dried foods. Or canned. But disasters are weird too, just so hard to plan for, a single major nuke meltdown makes all the plans collapse as you get an emergency evacuation notice. If I remember right, when Chernobyl blew, after hiding that fact for some excess time, the government basically forced everyone to leave with almost no notice at all, may even have told them it was temporary to avoid precisely the situation you are wondering about, people loading up excessively on their possessions and clogging the evacuation channels, don't remember the exact story, but there was really nothing you could do, it was go now, and never come back. Tsunami is the same in a sense, just bang, either you were in a safe area or you weren't. Earthquakes are a lot more forgiving, some stuff falls down but most of it is ok.
Re the homeless, I saw a lot of hobo types on my last trip a few weeks ago, range from normal standard, and important, cheap, heavy duty, gear, to middle aged lost looking guys walking down the trails with a black garbage bag. Saw a blue tarp and sleeping bag campsite by the trail, was told of other locations to camp too, so it was clearly a standard and known idea. But these guys don't care about ultra light, they just have their pad, tent, sleeping bag, and pack maybe, doesn't really matter what it weighs as long as its tough and durable and can take a beating, that was my impression. Or they are so lost they just stumble along with whatever they have in that black garbage bag. Ask the hobos would be my suggestion, not ultralight backpackers, the hobos actually live the life and know how to make it with almost no resources on a weekly basis, actually kind of impressed me to be honest.