I have got basic microtonal support working in gsharp, but it is not connected to the GUI yet. In the process I discovered a handful of bugs in the midi package and I have submitted them to the maintainers. It turned out that Christophe Rhodes (one of the gsharp devs) is the main maintainer of it. Once the midi package has been updated and if other gsharp devs are okay with my code I will commit it to CVS.
It has been a pleasure to work in common lisp. I could hotswap code without restarting the application, test things in the REPL, and the full numeric tower simplified my code in an unexpected manner. I had originally planned to have one class for equal temperaments and one class for linear temperaments for precision reasons, but the rational number support and the numeric tower made the equal temperament class superfluous!