Beta Channel is now open

If it follows the path of Canary and Developer and/or Google Chromes Canary, Developer, Beta, Stable than the Beta version won't install over the Developer or Canary version. It will be it's own self standing browser that can be used along side the others beta versions. Which of course is how it should be for those that want to use all three Edge beta's interchangeable, but separate from each other for testing purposes. You can have all three separate Edge versions if you want and use them independent as if they're three separate browsers. Of course you probably already know that but just saying because some people new to this who are only using one version right now (Canary for Developer) might believe by downloading Beta it will delete or over install over Canary which it won't. Firefox does the same thing with their Firefox Nightly and Beta and Stable version (you can have and use all three).

I don't know if Edge will allow you to convert your settings from Developer/Canary to Beta. If so that would be good. If not than simply go into Beta and set it up how you wish.  Google Chrome doesn't convert over your settings from Canary/Developer/Beta over into their Stable version or your Stable version over to Canary/Developer/Beta if you decide to try those out. It's not really a negative. Maybe a good option to add but if not I don't see it as a negative as you can set up one browswer (lets say Edge Canary) to be setted one way, and Edge Beta to be setted another way. 

(I'm under the impression once the Stable version is release Edge will still continue to have their Insider Beta, Dev, Canary channels like Google Chrome has done with theirs since 2011 so people can still continue to be beta testers of different levels).