If I'm reading it correctly, your answer is "just trust me."I see no conflict of interest. I have been around the block a time or two and know when I have written something that is crap. It would not be to my advantage to publish something of my own simply for self-gratification if it would hurt the image of the company as a whole. Hope that answers your questions.
The potential for this conflict of interest will always be there, for as long as the press publishes the owner's books. The perception that this conflict of interest is a problem will exist for many authors until the press has proved it to be otherwise. The reality that this conflict of interest is having/will have a negative impact on the press's other authors shall, obviously, have to remain as theory until it plays out one way or the other.
And the way that you've handled the reality -- the things you've put into place to remove that conflict of interest -- are:
a) you've stated you're trustworthy, and
b) "we typically market/advertise all Dark Moon titles as a unit."
The word 'typically' always gives me the willies. For some reason, I always turn out to be the exception to the rule. There's also the problem that while marketing may be done fairly between authors, what about cover art? Marketing? Distribution? Will the press owner's book get expensive original art on its cover while the other authors get slapped-on stock covers? Do you see what I mean? The potential for conflict of interest is there. If an author likes your book's cover better than his own book's cover, the perception of conflict of interest is there.
As for your assertion that you are wise, experienced, knowledgable, professional, and trustworthy -- sure, you probably are. But I could be wrong. You could be wrong. Derek Armstrong of Kunati Books was, by all accounts, wise, experienced, knowledgable, professional, and trustworthy, and his press was looking like quite a success. Until it all went pear-shaped.
Have a read of that press's thread and you'll understand why we're asking these questions. We're not trying to hurt you. We're trying to help you, and we're trying to help outselves and other authors. Seriously.