Interesting, thanks. It looks as though you rejected the idea of dual-licensing. It's totally understandable that you'd want to avoid the hassle, although a dual MIT/ASL2 really does give you the maximum protection and flexibility. There's at least one big open-source project that's recently taken this exact route:
http://thread.gmane.org/gmane.comp.lang.rust.devel/2593/matc...
...though in their case they were moving from MIT to a dual MIT/ASL2.