Has any one got a Fiamma Porta Cassette?

I am thinking of getting spare toilet cassette but I don't really have any storage for it.

I was wondering how strong the Porta cassette really is and would it hold a full tank ok? Not much point if it will only hold an empty tank!

http://www.fiammastore.com/Fiamma-Bi-Pots-and-Toilets/Fiamma-Porta-Kassett-Tank-Container