>Those are features that don't focus on the UX or the design. I think that build is labeled Aurora
Nope, Aurora is something else. It's the build after Nightly. Nightly includes pre-alpha releases, Aurora includes alpha releases.
You are however correct that Nightly and Nightly UX are not the same thing. Although if I'm not mistaken the only difference between two of them is that Nightly UX also gets pre-alpha UI changes as well as under the hood changes that Nightly normally gets (almost daily). It's a bit confusing.
I'm currently using Nightly UX. I've been using it for quite awhile and I haven't had any problems with it. That being said, you should keep in mind that this is a pre-alpha release and it wouldn't be surprising to run into some problems. If your browsing experience heavily depends on extensions, I'd recommend you not to use Nightly, though. I only use NoScript and AdBlock Edge as my extensions, but if you install 10+ extensions, you're not gonna like Nightly.
In any case, you can just install it and experience it yourself. If you're like me who started using Chrome because you were sick of how slow and unstable Firefox was, you'll be amazed how good it is now.
I've used Firefox all my life because of Firebug. Then after a while it just got so slow that it was unusable and the experience became terrible. And then I switched to Chrome. I'm not fond of their developer tools as much. Not as good as Firebug. I guess I'll give FF another shot.
I switched for the same reasons but kept FF around mainly for Firebug. After using and getting use to Chrome Dev Tools, it is actually no different and in some cases better. I don't do as much front-end dev as I used to though... But I do remember reading that the FF team worked with developers of popular plugins like Firebug to help make those plugins run better, use less memory and cause less memory leaks. You may find those plugins a lot better now.
I've been using UX on Mac and Linux for a few months – love the tabs in the titlebar on Mac – and rarely have problems. A few extensions aren't compatible, and occasionally a build is unstable, so I also have Firefox (stable) and Aurora installed. I just restart into a (more) stable release if there is an issue. They all use the same profile, so settings and tabs are shared. Lazy-loading for tabs make restarting not much of an issue, even with a couple dozen tabs open.
Which Chrome release channel do you currently use: Canary, Dev, Beta, or Release? I haved used Firefox Nightly as my primary browser for almost two years and have only hit a few major problems. Aurora is a nice balance between stability and new features and optimizations.
Nope, Aurora is something else. It's the build after Nightly. Nightly includes pre-alpha releases, Aurora includes alpha releases.
You are however correct that Nightly and Nightly UX are not the same thing. Although if I'm not mistaken the only difference between two of them is that Nightly UX also gets pre-alpha UI changes as well as under the hood changes that Nightly normally gets (almost daily). It's a bit confusing.
To sum it up, the release cycle goes like this:
Nightly (pre-alpha) > Aurora (alpha) > Firefox Beta (beta) > Firefox (stable)