Personally I'm a big fan of cans. The process which keeps MREs good for 10 years is very very similar to the canning process that's been in use for decades.
Can's aren't ideal for hiking due to the weight...or so they say. Never having handled an MRE I can't compare the weight new...considering how much water is in both, I don't think the weight would be all that bad. Plus if you pack out what you pack in, cans can become a burden.
In a survival situation cans give you post, cups, rain catchers, raw materials for building things from metal...it's great.
The only unknown for me right now are possible downsides to freezing canned food. I haven't been able to find anything on the net about this. Will it rupture cans? Will I be able to get frozen food out of it's can to heat and eat?
Makes me wonder what the military folks do with frozen MREs. I doubt the flameless heater is enough to thaw AND heat the MRE.
Sorry if I'm jacking your thread Susan!