tedster - 1:23 pm on Jul 3, 2012 (gmt 0)
My gut tells me that Penguin is objecting to something else, here. I'd still keep up the publicity and marketing for the new domain - but something else is probably the Penguin factor.
Look at the site from the average person's point of view and forget all about SEO for the moment. Do certain words show up on-page and in anchor text too often? Is other internal linking truly helpful to the user? Do your stats show good time on page and good average pages per visit? Those are the kinds of things I'd look for.