Anything over a bone is going to hurt more and outlining is going to hurt more too, however for most people I think needle shock is more of a problem than the actual pain. Make sure to eat about a half hour before you start and have water, juice, and snacks ready if you are going for the whole 4 hours. Keeping your blood sugar up is the best defense against needle shock I know of.

Also, and I know this sounds strange, but depending on how deep your meditative practice has gone you might want to be careful there - losing yourself if you do experience NS will guarantee you'll pass out right there. Did some shadowing of acupuncturists and I have some funny stories on why you don't combine the two...