I have not tried to box either of those classes, so I can't honestly answer your question, but I can say that both of those classes rely on special resources (Chi & Combo Points) to perform optimally. As multiboxers, we're already behind the curve in DPS, and my guess would be that it would prove difficult to get optimal multiboxing DPS from both of those classes through macros in addition to running a healer.

But that's just my guess.