[Filament]

I'm thinking also during the winter when it's colder it's not as suitable unless shipping by ground and very far away.

It'll still sublimate (even In an Ice chest) but at a slower rate, of which you need to calculate the amount of dry Ice against the transit and delivery time.

Of course - it'll never be so cold (at least in the US) where it wouldn't sublimate.
I'm thinking it's pretty ideal for most situations, other than in the cases where an empty box is sufficient, or it wouldn't be able to sublimate completely in time.