[bconway]

One thing to be wary of: abandoning the Mac App Store is going to make life much harder for you and your users in the near future. As of OS X 10.8, by default applications cannot be installed outside of the App Store (though a setting exists to change this):

http://techcrunch.com/2012/02/16/os-x-mountain-lion/ (scroll down to Gatekeeper)

Here's hoping that 10.9 doesn't disallow such installations at all (or void your warranty instead?).

[shinratdr]

Actually that's incorrect. You can't install completely unsigned applications from the web in 10.8 without changing a setting, but the default isn't the "Only MAS" option, it's the "MAS + identified developers" option.

So while you can abandon the App Store without penalty, you shouldn't stop paying Apple the $99 a year you need to do so to get the app signed, even if you aren't going to sandbox it or distribute it through the MAS. They just want the option of pulling a cert for a dev found to be distributing malware, not to personally review and reject every application that runs in OS X.

[bethling]

That's not quite true - as shown in your link, gatekeeper's default (at least for now :) is to allow App Store as well as Signed Applications. If a developer is willing to get their application signed, then end users will still be able to install the application outside of the app store.