No offense, but I think this is totally wrong idea...

BRDs (Machinist maybe too) are the DPS job with lots of "support" skills that help your party. MNKs are supposed to be DPS machines, that does help with DK and Mantra too, but their main goal to to just pump out DPS.

Having MNK sacrificing their DPS just to keep up TP, is wrong IMO... Ofc, if they balance it in a way that you would only need to be in that stance for a short period, and have high DPS overall in the fight, then it could work.

That being said, others still need TP song or Goad, and if BRD have to use it anyways, then there is no point in that stance...

Maybe there are a ton of changes in 3.0 that makes this viable, but I still don't like the idea of lowering your DPS on a MNK ever.