Android SDK emulates the complete ARM architecture. This does not. If you test your code in the browser, it doesn't mean it will run well on the phones. I wonder how Mozilla will deal with multiple devices in the future. At least Apple uses a simulator because developers can afford to buy all the more recent models.

Whether your code will run well on a phone depends on which browser(s) you test in. The entire apps stack is also being implemented in Firefox for Android (it was Firefox Aurora as of September):

https://developer.mozilla.org/en-US/docs/Apps/Apps_for_Andro...

In other words, Mozilla is already dealing with plenty of devices today. I'd expect that, in the majority of cases, if an app works well in Firefox for Android, it will work well on Firefox OS and vice-versa. After all, the whole point is to enable apps that are portable to any device/browser combination that implements the relevant APIs.

Different devices should behave the same in the sense that a browser on different operating systems behave the same.

Android SDK is horrible even with the recent updates.

You are far better off running Android in VirtualBox. It's small, really fast, and works like it should.

See: http://androvm.org/blog/

I don't know why Google thinks Eclipse + their shitty emulator is an acceptable toolchain. Must be all the Java devs there, they're used to abysmal start up times.