PPM works well for classes that have alot of instant attack, which fortunately Brewmasters are one of them. However, do note that most Brewmaster instant attacks are based off mainhand procs only. This can be evidently seen when you swap Colossus and Windsong between MH and OH. To that currently Dancing Steel will be the BiS enchant until 5.1 where RPPM kicks in. RPPM is not affected by instant attacks and will only proc based solely on weapon swings. In that case most probably Dancing Steel + Windsong will catch up.