This is just my opinion...

Does Modo blow Zbrush out of the water? No. They do very simular things. Just like Maya doesn't blow Max out of the water, or the other way around. 2 very simular programs doing very simular things. One might have a special doo-dad that the other doesn't but that's about it. User preference is about all.

Now how does Modo/Zbrush do against Maya and Max...just in terms of modeling, not getting into the rendering and dynamics that they offer...personally I would say Max/Maya still beat them out. Can you model in Modo/Zbrush, yes. But you definately have more control in Maya/Max.

Max and Maya are very high end programs and not for the light-hearted. There is a signicant learning curve to either one.
Most pros use Modo and Zbrush for fine detailing of an existing mesh...not creating one. Now I'm not saying they can't create a mesh, I'm saying most use them to detail.

Like Xenophonz said, it all comes down to user preference in the end.
Hope this helps

Comitted to excellence through art.