It would be fantastic to have support for non-standard tunings onboard. Something that would assign tuning offsets to each midi note / kevboard event (assuming the keyboard isn't generating voltages directly, which I doubt). Each table would be 128 values.
Interface-wise, they could be set up in the software, and then accessed with the matrix, using a shift mode (<something> + preset, perhaps). 256 tuning possibilities at our fingertips? (Maybe fewer, depending on memory available).
Since this would have to change the CV sent to the oscillators, this would, presumably, change the cv out voltage - which means alternate tuning control for external synths as well. Making the matrixbrute even more valuable as part of a larger setup.