Honestly, I use vim too, and I have learnt the "language" of vim i.e. the grammar and consider myself an advanced beginner.
I have doubts whether the efficiency gains are that useful in every day life. There will some days where I make some pretty widespread refactoring changes over files or the yanking/register stuff can be quite useful, but in general, every day programming, I don't see the efficiency gains.
I have another theory for why people like Vim so much.
Using vim makes you feel like the old-school, crazy powerful, very smart programmers shown in Hollywood. It makes you realize the dream that the little child had when he saw programmers on TV. ( at least for me ) and honestly, its more fun to be doing that so I do it. :)
Maybe I am not that good at vim. But at my level, i don't see great efficiency gains. I simply see more fun gains, and that's good enough for me.