Unless there is a multi-player add-on at some point, I don't think a gold membership is going to help any. There have not been any add-ons yet (or any announced) or bonus content (other than pre-order downloadable items), let alone anything exclusively for gold. As far as I know the demo didn't get release early to gold memberships, either.
Coming from a PC developer background, I wouldn't expect Larian to release any significant content exclusively. Although, I suppose if Microsoft showed up there with a request and a dump truck full of money...
