Dogfooding is great and important, when it affects only you.
When you force it on others, particularly new users to Tiki in the Forums (typically one of the first areas of 'on-boarding' new users), probably not the best idea, IMO.
When I took a look at other Forums, the vast majority use the same exact one (no idea what the app is called), and to be honest, it's not the most user friendly - typically very tiny text, old design. So Tiki's Forums do have a very unique and individual look, and better readability, however, are space in-efficient. Like many parts of Tiki, Forums need a complete re-design/overhaul, not patching.
What are you trying to achieve with the sub-Forums?