I can't speak directly about your tool since I haven't tried it, but regarding latest Zbrush box modeling tools, I speak from direct experience with it - it's a step backwards regarding box modeling. Everything takes 10x more time to do than in a traditional (max, modo, xsi, even houdini.) poly modeler. It's better to have box modeling in Zbrush than not to - it gives one more option to those artists that are using only Zbrush - but on an absolute scale, it's crap.
Yes. You are right. with ZModeler user need to do more actions acoording to classic modeling, especially more time to select tool\target. But my tools have a classic modeling style (more like xsi) except it have more powerfull selectors (like “Flat Island” in ZBrush). But of cource you can see this difference better when it comes with more polytools. I think it woluld be very fast and intuitive tools