I've never understood this obsession with editing efficiency among programmers. When coding I spend about 90% of my time thinking about what to type. A good IDE that really understands the structure of my code without twenty flaky plugins is worth much more to me than saving some keystrokes.
Typing efficiency I'm "meh" on; don't get in my way, but I'm not too worried about it. I've tried tons of autocomplete of every kind and tend to just turn it all off. Navigational efficiency is very important, though. If I want to look at a bit of code, fractions of a second count if I'm going to stay in flow.
This is very much personal opinion, but what I found with autocomplete is the time I'm typing the code I'm also using to think about it. Even on those surprisingly rare occasions where I manage to set up autocomplete that is both fast and accurate, it still didn't speed me up much. If I'm thinking so far ahead of my typing that I'm actually frustrated about the typing, that is typically an absolutely enormous code smell that something is very wrong, and I need to address the redundancy immediately.
I think it depends somewhat on the language. For Ruby I prefer Emacs and don't see much benefit in autocomplete. But for Objective-C & Cocoa, which is admittedly a somewhat extreme case, autocompletion is a godsend.
But autocomplete is only one feature among many I appreciate in a good IDE. I'd also hate to give up a good visual debugger with integrated breakpoints, direct links from compile errors, etc. I know you can hack a lot of this together in Vim or Emacs but after 15 years of doing just that I don't miss it when I'm using IntelliJ or XCode.
I don't. I do my thinking in the code because I can edit fast enough to keep up. I test out ideas as they come to me, delete them, refine them in the code itself rather than think up abstractions and then translate them into code in a second step.
