Yeah, the whole merging thing sounds good, especially since I was just in the same position earlier today. ^v^ It's also got some downsides, like the topics may me very similar, but still have differences that would conflict in the same thread, or an ongoing conversation would be cut off by sudden off-topic posts.
Really, this should be a poll, so that we can vote if it's a good IDEA, and after that, it's still up to the admins.