It definitely looks like a cool app, and I was excited to test it out, but I don't have a Mac. If you ever hit the point where a rewrite makes sense, it would be awesome as a universal app.
One idea I've been toying with would be to do a Kickstarter-style campaign and if it reaches a certain threshold, then I know it would be worth porting.
Targeting Windows/Linux/web still means I cannot re-use the sources. But targeting web might be faster in terms of development time, although I don't have deep expertise on non-Apple platforms, so I cannot say for sure.
