What I do not know - is if 1) this software is truly capable of allowing a single website to be written once and exported to Hosted or Packaged Native Apps.
3) Is it simple, or is it painful? Has anyone seen a full implementation first hand in at least a test environment or production?
Also - are the upsides expected or unexpected - and what are the downsides?
To the point it isn't 'Native' - I found these.
I installed a FireFox OS Open WebApp with emulator. https://developer.mozilla.org/en-US/Apps/Quickstart/Build/Your_first_app
I don't know what these are, but it was easy and it looks cool. Like a website packaged into a Native App.