I think I've brought this up before, but since we're on the dawn of a whole new look around I'm going to resubmit this for your consideration.
What if the donating member off topic forum and all the treads were visible to non-donating members but the thread was not accessible to them? They would be able to see the topic of the thread but when they click on it they would get a "To view this thread please become a donating member" sort of message and maybe a link to the donating member page.
This would in effect become it's own advertisement so non donating folks could see what topics are available before paying for it and it would answer all the "what happened to my thread" type posts because they could see where it was moved to, but they would get the above message when they click on it.
What do you think?