Regarding the point about autocompletion: If autocompletion is needed don't use vim or emacs, -use Netbeans or eclipse, both excellent, free (both ways) and open source. vim is great and I use it all the time but not for Java and PHP where the IDE support is so good that it really makes a difference.
It actually works so well that the "emacs eclim", based on eclim, "Just Works! [TM]" and gives you, right inside Emacs, the Eclipse auto-completion.
Even when stuck in the Java/ORM/Hibernate/SQL/XML hell (at which point I want to kill myself and really question the company's "productivity"), I'd still rather use Emacs + emacs-eclim then Eclipse (or IntelliJ IDEA -- which gives both NetBeans and Eclipse a run for its money btw).
Thing is: adding Eclipse / IntelliJ support to vim / emacs is not that hard. But turning the "text editor" part of Eclipse into Emacs just looks like mission impossible.
IIRC using eclim you can replace the (very lame) text editor of Eclipse with vim. So you get vim running right in the middle of your Eclipse.
What's not to love there?