When playing the Monk I feel it would be better if switching stances was a fluid change for RP and Mechanics wise. It would be nice if you could in combat switch from crane to tiger instead of waiting for combat and the stance affect to drop. It's not like Marital Artists wait hours so they can practice a different style, so it doesn't make much sense for me that you have to either.
Monk Change
How about revamp them a little and give them some selectable paths?
But on topic, you can switch stances by empowering opposite stance, then attacking a mob to break out of empowering, then rempowering again. This takes a total of about 2-3 hours with the risk of being attacked with no empowerment. Perhaps they can alter empowering time from 2 hours to 1 hour? Also reduce the limiter of being able to change stances at 18 hour mark perhaps to allow for the switching.
I am not sure that is a viable solution, as part of the balancing aspect to monks is that they are extremely vulnerable when not prepared. By lowering their downtime, you are effectively increasing their power. Not really what we want from a class with the potential for complete lag locks.
Speaking from experience of playing a few monks, it's pretty easy to bait, run and elude the player that is attacking you whole empower thing works quite easily, even empower your opposite stance and re empower works easily