IP.Board 4 is currently stable and, honestly, it has a lot of improvements to make IP.Board much more friendly. The main reason why G2G's forum can sometimes be a problem is the issues in the software itself, an example being the editor. IP.Board 4 is in stable release, and if you have an active license an upgrade shouldn't cost anything. Probably some prep work if you have add-ons installed, backups and a scheduled time as well. Shouldn't take more than a few hours at most.
Personally, I think it'd be a huge improvement to both user experience and moderation/administration.