NavList:

Great clip, but try it, take an ordinary BIC or Pilot ball point.  Hold a pad of paper over your head and write the following:

"Gravity is the law, but most pens will write perfectly upside down."

Bet you it'll work.  I write in my journal holding it over my head while lying in my berth. 

But face it, the only problem with a pencil is that the point breaks or wears down quickly. 

Ik is permanent, pencil graphite can be erased.