Hey Eric - thank you throwing out some feedback. I agree that we have grown from our humble 3 categories to the 9 we have now in short order. Most of the reasoning behind why we have more categories now is to help visitors find information easier.
For example, we had a lot of great fabrication posts that were ending up in the servicing or operating forums and they would get "lost" in there. Instead, if we divide posts into a bit finer granularity according to a category they get more attention and are more likely to get responses.
I think the categories we have now should suffice for a while. If we start to get a lot of a new type of post ending up in one spot (ie. 500 or 1000 new member introductions) then we might consider making a new category just for those. It is a balance - we do not want to spread things to thin but we also want to make the site easy to navigate and friendly for visitors.