I think the idea is Nightly/Aurora/Beta builds aren't just for Firefox Developers but Web Developers too and it would be beneficial if more web developers used

I think the idea is Nightly/Aurora/Beta builds aren't just for Firefox Developers but Web Developers too and it would be beneficial if more web developers used this branch for development. Of course, don't forget to test in stable. Another thing I can think of is rather than prefixing CSS/JS, experimental features could always be enabled in the developer builds and it then kicks into life on stable when it's ready for the general public. Right now you need to change various flags for that to happen.