More importantly, if I've selected "Always", how do I change it back to the old way later? Are intents something I can access and change in the normal system settings?
Well, there's still a pain point there. To change it back to the old way you have to go to settings, then hit "Apps", then scroll to find the home screen app you no longer want, then hit its "Clear Defaults" button.
There's never any text that explains "this will let you choose a homescreen again", or really anything that will help you know to look for the Clear Defaults button.
Uninstalling it will also accomplish this, which I expect most people will do if they want to get rid of it. I do agree that it should be more straightforward within Settings, though; It would be nice to go to Settings > Home Screen and have the first option be something like "Choose which Home Screen software to use".
While that works in this case, it's only because Facebook breaks their functionality into multiple apps. If "Facebook" registered a homescreen, instead of "Home" registering it, then how would you remove the default? Sure, you could uninstall facebook and then reinstall it, but that's a pretty painful workaround.
Another use-case that should be fixed, the instagram app has registered to intercept browse intents for its domain. So, clicking on a link in twitter will show you that picture in the instagram app. The problem is when badly written apps do this, urls like http://instagram.com/developer/ will also open the app, but it will notice it doesn't know how to handle that url, and either quit or crash.
Sure, developers should know better. But I'd really love a way of saying "for the next intent that fires, let me chose the default again".
You could toggle this flag and then hit home to reset the homescreen app. Or you could toggle this flag then hit an instagram link and say "just for this one link, use chrome".
Unfortunately, while that would be a fantastic tool for developers, it's probably not a practical solution. There are enough edge cases that it would be hard to implement, and very hard to educate users on how to use.
I've always had a ton of problems with defaults and intents. To this day I still have certain intents that ask me every single time, no matter how many time I choose a default.
