For any Eclipse users here (can't speak to any other IDE), many of Eclipse's features can be invoked headlessly. For a year or so I did most of my Java dev in Vim because I had to work on a remote server, and Eclipse was unusably slow over X11 streaming, but I still had a keybinding that triggered the Eclipse formatter on my open files. I'm sure many other options would work, though I'm sure some just won't. I just used ctags for autocompletion, and I was happy enough with it. Only works if you already have a good idea of what's available, though.