Short answer: no, it's not worth it.
I'm selling the same app on both Ubuntu Software Center [1] and Mac App Store [2]. Between June and December I have sold 29 licenses on Ubuntu store and ~2000 licenses on Mac App Store.
Chrome Web Store [3] seems to be a much more promising distribution channel for Linux apps. With the new APIs it will be possible to access native window manager, USB ports, filesystem or webcam. Besides, you don't have to deal with incompatibilities between distros.
[1] https://apps.ubuntu.com/cat/applications/type-fu/
[2] https://itunes.apple.com/us/app/type-fu/id509818877?ls=1&...