Funnily enough, I'm going to other way: long time Emacs users, getting closer to switching to evil-mode (Vi emulation in Emacs). Doubt I'll ever leave Emacs though.
As an aside, how does one keep up with Emacs package development? There is lots of stuff that's new to me (e.g. I just found out about company-mode). I'd like to have some way to have this information pushed to me, rather than having to go searching.
evil-mode is actually pretty good. I've been using it for clojure (paredit is quite nice). Keep in mind, though, that not all packages are gonna work as expected (I had problems with multiple-cursors, for example).
Something I would really recommend you: there are a lot of people in vim (like me) that have remaped the ESC key to a combination of keys (in my case jk); that is, by pressing j followed by k you go to normal mode (it's actually way faster than having to reach ESC). In vim, such thing is very easy; in emacs, you need to install the key-chord package, and something like the following would work:
By the way, regarding company-mode, I think autocomplete is newer and it's what most people are using nowadays.
I found out about a bunch of plugins through emacs live and prelude (and then switched to my own config). Take a look to other people's config on github :)
As an aside, how does one keep up with Emacs package development? There is lots of stuff that's new to me (e.g. I just found out about company-mode). I'd like to have some way to have this information pushed to me, rather than having to go searching.