I've looked at the SIGG boxes (at that very site as a matter of fact) and decided that the lower profile BCB box would be easier to slip into a jacket pocket.

But now you've raised an eyebrow... I just recently started carrying a gallon of water in the cab of my truck in the form of 4 quart-size polypropolene (Nalgene) bottles, realizing that they will be 4 cylinders of ice for 3 months of the year. Are you saying that aluminum bottles would have been preferable because one could apply heat to them directly to thaw them out? I was afraid that the ice would have bulged out the aluminum bottle, possibly splitting it.