I use JKLI. The two main advantages are that you don't use your pinky finger repetitively, and the layout of JKLI makes intuitive sense as to what each key does.
Unless you use Dvorak. I know I'm in a super minority here. But shortcuts based on keyboard location rather than tied to some mnemonic are damn near impossible to get right. Doubly so when I have to switch to QWERTY to work with anyone else.
I switched cold turkey to Dvorak and Vim at practically the same time (what can I say, I like pain :) I learned Vim mnemonically and have no problem using Vim on QWERTY. At the same time, I could have just as easily learned it "locationally" and been screwed. Only chiming in because I think it's interesting that the learning curves for location-vs-mnemonic seem approximately equal, but the long-term payoff of one is much greater. Neat asymmetry.
Good point, not sure what I was thinking. For me the strain of moving my index finger from J to H is more than the strain of moving my middle finger from K to I, but that's probably quite subjective.