I'm in the minority camp that doesn't think arrow keys are a big deal, but I suppose I need to qualify that and say "not a big deal if you are on a Thinkpad" and you have an solid reach of curled fingers in your right hand. There's are efficiency gaps in between

  1) keeping fingers on jkl;
  2) manipulating the arrow keys with fingertips, 
     primarily using the pinky for quick movements
  3) lifting the hand to use the arrow keys

and they do add up over time, but I'm not sure how detrimental they are.

Sometimes, the arrow keys provide a nice mental break, where you can step back from the doc and examine what's happened so far with the arrow keys or page up/down.