The difficulty in reading forums on dark backgrounds is something that I've met up with quite often too, so it'll probably be an "option" rather than a default layout. I've seen how some posts look and it may need a bit of adjustment. Apart from that, yes, it looks brilliant.
I hadn't thought of a different logo other than the existing Broomsticks And Owls logo but it's a good idea to have a competition, showcase or voting thingy. Because of technicalities of this, it'll have to be after April (I should have a lot more time available to do stuff after April whereas at the moment I need at least 48 hours a day to fit everything in!)