Just thought I'd chime in on this there are several factors to becoming a mod, however all of those factors are superseded by the needs to have additional moderators on the forum. At this time the moderators got things well under control and there is also a list of frequent and participating members interested in becoming mods when spots become available.
Time spent on the forum is not even something I really consider when looking at a user interested in becoming a mod, since I realize everyone has lives outside the forum and I of all people know you can't be here all the time.
Some of the top things I look at:
- Quality (not quantity) of posts
- How knowledgeable the user appears to be based off his / her posts.
- How well user gets along with all users on the forum
- In some situations the times that they're on the forums. This helps make sure at least one moderator is on.
Of course before anyone is accepted I always bring the final decision to all current moderators and get their final say in the matter.