Well, I imagine from a design standpoint, the Filmation designs are always simple and clean, and easy to sculpt. I speculate that this is why we don't see too many 200X designs(that and other legal reasons). Those designs were a bit too busy and gaudy. The amount of extra sculpting and paint apps that would be needed would be too much.
I still think Granita will be one of the 6 of the Filmation Sub. Sea Hawk, Granita, Madam Razz, Icer, Batros, Shokoti...