Even opposed, the Pull power seems to be to good not to use, in any circumstance. While testing the Pulse Stun on the Cerean's staff, 2 of my players had a duel. After 2 rounds of combat, the opposing player, just backed off and used pull to disarm the Cerean. The player doing the pulling had 4 Will with 2 rnks in Discipline, and the Cerean has 2 Brawn and 0 Athletics and 2 Will and 0 Discipline. Way easy.
The general consensus was that it only happens in the movies once, Vader vs Solo, and only against a non-FU. One of the players thought they remembered Ventress doing it to a Jedi once in the Clone Wars, but other than that, you never see it elsewhere. If it were simple why wouldn't Qui-Gon just Pull Maul's saber from him while he was across the room before the battle was joined, or Vader simply pulling Luke's saber in ANY of their battles? This makes you tend to believe that it was never thought of (Honor type thing) or it was too difficult or dangerous to do.
My solution wouldn't have helped much in the player's duel, but would explain why it was almost never seen in the movies. If Pulling from another FU, a black die is added to the opposed roll for each rank in Force Rating.