I will definitely try Mac AppStore. Out of these 30%, you will spend at least 10% on billing, hosting, etc. if you distribute yourself, and you will also spend

I will definitely try Mac AppStore. Out of these 30%, you will spend at least 10% on billing, hosting, etc. if you distribute yourself, and you will also spend some time doing that (or posting PayPal horror stories to HN). I think the AppStore's wider audience reach will more than offset these mere 20%. Also, we should expect significant price drops for desktop software (competition), and ignoring that will make your app less competitive, whether you're on AppStore or not.