Have you considered the relative SPLs of your woofers versus the ribbon? The 30Hz to 300 Hz range needs a lot of Xmax for the same spl. Your Gold Ribbons probably can pump out the spls if they are anything like the B&G planars.What max spl are you shooting for?
(As an aside I don't know anything, good or bad, about trinaural--I use a phantom center).