What else do you plan on using the reserves for after the new forum is done? If you plan to keep Slickage working for bitcointalk indefinitely, I'm totally fine with that as an answer to that question, since those guys do some pretty good work. Otherwise, it's kinda silly for a forum to have several million dollars in reserve.
I don't intend to indefinitely spend this much on software development. The reserves should be used for Bitcoin development and other things that benefit the Bitcoin community. In a year or two, I'd like to see the forum organization (maybe renamed to something more appropriate then...) hiring a few developers to work on Bitcoin full-time (focusing especially on the technology) and creating frequent bounties for smaller projects, but still maintaining a large reserve to handle emergencies which affect the forum itself or the Bitcoin network/ecosystem.
(I do have a natural tendency to maintain a constant surplus and save as much as possible, even when this is maybe not correct, so someone should complain to me if we reach a situation where the forum has a surplus and still has a reserve of 5000+ BTC. But right now I think that the spending level is about high enough.)