@mmoening, please accept my comments here as friendly feedback (it's hard to tell in an email).
I find the quality / material methodology to be the most confusing feature of MatterControl. I've had the software for 2 years now and I still find myself scratching my head to understand the paradigm.
From my view, there is a certain expectation that software such as MatterControl should be rather self-explanatory. I don't see anything that is so complex about material / quality settings that would warrant the confusing implementation. My take on the implementation is that it is designed from an engineering view rather than that of an average user. Surely there is better way.
That said, I think overall the team has done a good job making the software easy too use; I particularly like the "Show Help" option.