I'm in the same boat. My brain thinks in vi, and coding with different keybindings is like trying to translate to a different language during a conversation.
I used viPlugin for a few years (up until 2008), but always had the impression it was masking lots of Eclipse goodness in terms of completion and lookup functionality and I just eventually reverted to command line vi again.
I'm going through a trial with Komodo right now, and I'm tempted to spring for the full blown commercial license. It builds in vi emulation, so it's a ground-up approach rather than some tacked-on add in.
Another path you might consider is taking steps to make vi more IDE-like, ala...
http://arstechnica.com/open-source/guides/2009/05/vim-made-easy-how-to-get-your-favorite-ide-features-in-vim.ars