Hi Zymon, well MoI and ZBrush are based on very different technologies and have very different strengths and weaknesses.

MoI is a type of CAD program that can be used to design precise parts primarily generated from 2D curves.

ZBrush is a type of DCC program that can be used to sculpt complex organic shapes.

It won't work very well to try making complex organic shapes in MoI nor will it work well to do precise machined parts in ZBrush.

From what you are describing it sounds like MoI would be a better fit for you, you should get the trial version and test it.

If you could post some examples of the type of thing you're trying to build that would probably help to give more precise advice, there are some styles of objects that are in a kind of gray area not entirely organic nor entirely mechanical.

- Michael