When you now autocomplete server names like:
It autocompletes to:
However if you have the matching key in .ssh/config yourserver you want to hit it first. This is because SSH config entry have username, agent forward, etc. related configured.
it DOES complete from config, but also it does not even show the completions on menu before you type... Also I think it depends on whether or not you have encrypted the knownhosts file...
did I fix that btw?