I did Mythics last evening. I've got to say that Brewmaster is just an offspecc for me, I main Windwalker. We managed to run the dungeon without a wipe, but it was really hard for me to stay alive. I tried to keep up ISB, but failed when I needed to purify my yellow-red stagger. In result, I had no more ISB left and the mobs just hit me unmitigated, because there was nothing I could do against till I had a new charge of my brews. I had to spend the new charge directly for purifying brew, because meanwhile my stagger became red.
I felt really helpless and all I could do was praying that the healer managed to keep me alive.
That was definitly the last time for me to tank as a Brewmaster in Legion