I have considered it, decided not too. But I might change my mind, they are cheap.

The problem I see is that a sack gets smaller as you eat the food that was in it, and that aluminum sheet would keep the sack big. Thus, one of the big advantages of the Ursack over a hard canister disappears.

If I traveled to some places where the aluminum was needed for regulatory purposes, I would have bought it years ago. I have no such plans. If I need it later and they are no longer available, I would probably rent or buy a hard canister then.

I use an Ursack primarily for protection against smaller critters, like mice, raccoons, and chipmunks that can get into your food. And also because if a bear gets my Ursack, they might crush my food, but I am not training the bear to go to campsites for a source of food. In that case, my crushed food that a bear did not get to eat is a benefit to future campers, not me. There is no question, a hard canister is better protection, but I have never had a bear get to my food yet, so I only would get a canister if regulations required it.

I am packing for a backpacking trip, leave in about a week. Yesterday, my Ursack (XL size, 15 liter), a REI brand 15 liter drybag, and six days of food weighed 5.29 kg, or about 11.7 pounds. The bag had a little empty space in it, could hold more than six days. When I have used that Ursack for a nine day canoe trip, the Ursack held about 7 or 8 days of the food. Theses quantities are all for a solo trip.

Backpacking, I carry food that just needs to be heated. Butane stove, minimal fuel weight or use. And light weight foods. That said, my Dr has cautioned me that I need to get adequate protein on such trips, so I have a couple small packets of meat every day too. Along with a 20 gram protein bar per day.

Canoeing or bike touring, besides dehydrated foods, I am more inclined to carry food that uses a fry pan (eggs, fried meat), or maybe pasta that needs extended boiling. Liquid fuel stove on those trips if I did not fly somewhere. Bike touring, might buy canned foods too, such as a can of soup or chili, etc. The weight and bulk rises for such trips compared to backpacking.

Packed up my backpack yesterday to wear on a three mile hike, about half of that was through a hilly park. To get the food to fit well in my backpack, I had to take about a third of the Ursack contents out to pack elsewhere in the pack. A canister would not fit well in that pack, and the aluminum sheet in the Ursack would not fit well either if I had that. On my trip, I have one resupply at a mid point, so about a week and a half long backpacking trip.