They will coexist perfectly fine. In fact, I have both installed on this site and there are no issues at all.
You just can't use both on the same page or post.
Hey Adam, I was thinking of trying out Elementor as well with the unlimited site version license.
I have BB Agency, BT and UABB, Astra Agency. Can I take a BB Theme or Astra Theme site that was already created in BB/BT (headers/pages/posts) and then start re-editing them in Elementor?
In other words, would it continue from the existing edited rows, or would the content looked skewed and I have to start over basically?