Edge is available at least on OS X, I'm currently running it on both of my Macs. Not sure about Linux though and I agree it'd be great if they open-sourced it.
The chromium base is very well supported, I like and am familiar with the dev tools, and the battery life has also been much better than Firefox on OS X. I would prefer to use Firefox for everything but I run into enough small issues that I prefer to use Edge. I'd run Chrome if it didn't have so much of Google hidden in all the nooks and crannies.
