Well I get the impression that the basic idea is purely for you to be able to buy just the parts you want and build the system the way you need it, as opposed to their other PCs which obviously just come as a more conventional setup in one package.
I've got a couple of Strandhoggs and some AAC components that are currently in the hands of my custom sewing guy. I always place my orders with FS via e-mail rather than through the site itself and when I got the invoice it actually said Amphibian rather than AAC; the Amphibian being a Strandhogg-a-like with slightly different materials designed to soak up less water as well as shedding it more quickly (along with some other differences 'designed for naval spec ops cool dudes' from what I remember of the product description). I just checked and the Amphib is no longer listed on their site.
I only have the AAC back panel, but it lacks the perforated foam pontoons that the Strandhogg features, which is a shame as they make for what is no doubt one of the best ventilated carriers on the market.