Multiple levels of opting in?
1 Core software / patch developers
2 Userspace app developers
3 Really enthusiastic enthusiasts with cavalier attitudes
4 Chilled out enthusiasts
5 The paranoid-but-nosey
6 Dave999
7 Public release

And I don't want to prevent anyone trying anything, it's just sometimes people post the steps to switch update sources without any disclaimer, and not everyone understands that it's not finalised software to the level of testing that might be expected, and then they're forced to become a fisherman to fix their phone, and not everyone wants to spend the day smelling of fish. Hmm this analogy might be breaking down...