From an overarching level, merging OA with PA is a good move, since now people don't have to go to another forum to post anime related topics. However, on a personal level, I'm not particularly interested in adding the task of shifting through a lot of pokemon-anime related topics to just to find the few non-pokemon anime related topics.
Although seeing OA's activity (and my own activity for that matter) I guess no one else really thinks of this as a problem.
If these two get merged, will their title be changed to something like "General Anime/Manga discussion?" If so that might give OA at least on even ground with PA *wishful thinking*.