i suggest a option for Monks/Any class with such drastic changes the option to pick which format they want :
a) to remain with the old system, with 10% bonus to avoidance
b) the new system with the combo system updated
in other games there are levels at which a class can change to a different sub class, via a quest or something, or perhaps when you create the monk, you can give the option then, or have it in game via pp or something, anything could work really.
This way, all monks would be happy, new and old, and if the devs really want to get people to use the new system, all they have to do is make it more attractive than the old.
Also, options are always fun, this way, we could have real variety not just via gear, but what sub classes are being used, more options = more fun?
God Bless you!
May Jesus Christ be Charitable unto you