Well, a few thoughts.
As the current administrator of a fairly high traffic PHPBB elsewhere, and a long-time message board and, previously, Usenet whore (with >10,000 posts on a few different boards at this point), I've got to say that I think fully empowering prominent community members to maintain order in the community makes perfectly good sense.
Inevitably, there are always people who complain about moderation when moderation is essentially controlled by members of the community itself - hell, there are always people who complain about moderation regardless - but it's presumably the best solution here.
I've found that boards whose moderation is directly controlled by paid employees or a selection of employees are often more chaotically problematic, simply because the board gets an anti-establishment mentality subject to which problematic moderation is consistently blamed on the company itself. A fan-maintained, fan-moderated community redirects antagonism away from the development house itself, even if it merely redirects it at members of the community (antagonism will be directed somewhere, it's just a matter of where) which can be beneficial.
And incidentally, as for developers being bugged to post and respond to PMs, it seems to me that under no circumstances should a developer be expected to perform a consistent public relations function in this kind of way, in this kind of environment, and sane fans know this, so this should be beside the point. Were I developer on such a board as this, frankly, I would simply disable PMs to all developers posting within the community, because it's not worth the hassle, nor should it be expected. PMs regarding message board administration should be directed at moderators and community leaders.