Thats a really checked out idea with the heat can dude. Nothing worst that trying to do stuff with frozen hands. Have you tried it in the field yet? The only concern I would have would be if the string pulled the tab off of the can without opening it just like those dammed fruit cups. Then again, its nothing that you can't solve with a good twist of your knife.

Lets us know how it works for real.

I may end up attaching them strings to my beer cans on my next hike. Those suck to open with cold hands as well.