I am currently multiclassing as a monk/ninja in my friend's campaign. This build seems to be an effective build. Using Wisdom instead of Charisma for ki is nice, and using sneak attack on fury of blows is amazing. The two classes are very similar and stack nicely.
When I first heard of the new hybrid classes, I anticipated a monk/ninja or at least a monk/rogue to convert my character for a better build. I was angry when I did not see the build.
What other combinations have not been made, and why does this build not exist?!?!