You've got "Trilam" and "Cordura" as separate options, but most suits made with Cordura are of trilaminate construction. For instance, the DUI CLX450 - "The upper body fabric is a trilaminate material made of Cordura® blend / butyl rubber / polyester." A handful are bilaminate.
Either way, there aren't any drysuits made of "just Cordura"
Same here.
---------- Post added December 6th, 2013 at 08:54 PM ----------
And I can assure you that, as water is neutrally buoyant, it cannot "offset the buoyancy" of anything.