Obi-Wan was saying the truth about the higher ground... Yes, Anakin is more powerful than Obi-Wan and yes he did have the advantage on Obi-Wan on some occasions because of this. But overall, they were pretty even because Obi-Wan is more experienced and more importantly, in control of his emotions. Remember, they fought for about 10 minutes or so, which is pretty long for a sword fight.
Anyways, the bottom line is than Obi-Wan didn't want to kill Anakin, and that's why he told him not to jump, because he knew he had the better position. Not to make him jump and kill him...