My philosophy is, having the supplies you need, when you need them, is worth the effort it takes to bring them with you. The gear is held on by simple cambuckles. If I had to cross somewhat deep water, or get over a large fallen tree (assuming I couldn't just go around) there's no reason why I couldn't just undo the straps and carry each piece of gear, one at a time, over the obstacle and then strap it on again when everything is on the other side.

The only real restriction I've encountered is the width of the cart means I can't squeeze between tightly grouped trees. But there's always another way around. You just have to be willing to look for it.

It's a great rig. Have you thought of a bicycle attachment?

You could haul a substantial anount of water with this as well, if you could find containers that stay on.

Sweet...You're now ready to go see The Road this weekend.

From the side, it kinda looks like a Segway. Do you have anything to cover it up with to keep out the rain?

I think you have a really cool setup going there; it looks like a fine way to haul a lot of gear.
My first thoughts were "man, I should put together something like that". But, then, the other side of my personality kicked in, and I started thinking about whether I would want to call attention to myself in a "bug out" scenario. I am afraid that if it came time to get out, I would spend too much time trying to decide if I really wanted to haul that much stuff with relative ease, or if I really didn't want to call attention to myself as "the guy over there with the cart loaded with goodies".
So, there's a lot of things I like about what you've put together there ... but, my own character/personality has me struggling as to whether I would actually head out with it; or would I end up wasting more time trying to par it down to what I could carry on my back. (?)
I will have to try to think this through some more.

I'd have to hire a Sherpa to haul that.

Impressive, though. Thanks for posting the photos.

I've often thought those game haulers would be useful in such a situation.

And I've wondered what I could do with my golf pull-cart.

But I'm most inclined to start with my bikes and bike trailers (a Burley Nomad and Croozer dog trailer).

"...golf pull-cart.."

In his book Worldwalk, Steven Newman used a golf pull cart to lug his gear across most of Australia. Seemed to work pretty well for him. Slightly smaller diameter wheels that the OP's cart tho...

The first thing that popped into my head was either you are planning a 200 mile bug out on roads or you are bugging out with 8 kids.

Me, family of 4, 60 mile bug out. Medium alice, and everyone else with daypack.

How far is your destination, and over what terrain?

Shelter
Fire
Water
Clothes/Bag

all I consider critical and would make sure I have them in my pack. What is filling the large alice?

I wonder if you could do something similar with a bike trailer?

Teacher--and others.. i was thinking the same thing myself.and when the going got too rough for even a mountain bike you could stash it away and go on foot with the trailer..and..when you could not make it with that backpack the rest of the way..sort of a three stage rocket effect--

Just setup similar myself. Bought two mountain bikes off of craigslist and a burley trailer for the kids. Were getting setup to use them if needed. going to hit the trails around here once it warms up. Enough room in the back of the trailer for our bob's though I'll probably ride with my backpack on me to help distribute the weight some. I have a handheld gps and am ordering the handlebar mount so I can log our rides and see how far and how fast we go so I have a level set for bugging out.