I like 2nd Edition and 2.0 equally, I think, but I believe they bring different expectations to the table.
With a 2nd Edition, people are going to assume a degree of incompatibility, while 2.0 feels more like it’d be an upgrade to the existing book (similar to Redux or Remastered or whatever).
Either way, I’m excited about more Monolith!
I also have the impression that talking about editions probably communicates a major change, but I'm not sure it necessarily implies incompatibility. Cairn 2e added mechanics, procedures, backgrounds, while keeping the core rules intact; although it could have been an expanded edition, I think 2nd Edition works well in that case as well.
