I don't care about the backend and how it's implemented. I don't write IDEs. I write software in IDEs. If the IDE is good, and by good I mean provide autocomplete and features on par with Eclipse for Java,and it needs to be fast and easy to use.

Fast and easy to use are UI tricks that can't be handled by a server.

Edit: I just realized that this may be read in a negative connotion and I didn't mean it like that. I just mean that I'm not the person who should be looking at those. I just know it doesn't exist yet and I'd like it to. Telling me of the Rust Server thing gives me no information as to how close the IDE is to being done.

The only thing the RLS is going to provide is just faster completion for the most part. All the IDE's in existence right now are making use of racer for completion and clippy for linting quite well without it, especially Atom.

The point of that comment was to say "It's being worked on, actively"