Personality Conflicts

In the post on intelligent magic swords with Ego scores, I put together a modified version of the mechanic for determining which side dominates the other in a battle of wills. My modified mechanic used a situation roll instead of the percentile roll in the LBBs. This seemed a good choice, since it reuses an existing rule and makes the system more integrated. However, I could go farther, taking the rules for magic swords struggling for domination out and making them apply to stubborn/bossy magic items or animals in general.

An otherwise loyal animal or magic item may stubbornly attempt to take charge of a situation; give the animal or item a Willfulness attribute of 1 to 12. For general behavior, modify the roll based on the difference between Willfulness and the character's level; for critical situations, add any Intelligence score to both sides and replace the character's level with an appropriate attribute, usually Strength for controlling an animal/item physically.

This raises the question: should I keep it as a situation roll, or should I use one of the other mechanics? The breakdown of pros and cons for each is:

Situation Roll: use half the difference as a modifier.

• PRO - modifier shifts odds in equal steps; different beasts or items can be defined with different situation targets easily.
• CON - have to remember to interpret roll from the perspective of the weaker side (avoiding accidental loss of control.)

Morale Roll: use difference as modifier; beat Low result if animal/item is weaker, High result if stronger.

• PRO - fits best conceptually with morale rolls; no multiplication or division.
• CON - modifier shifts odds in uneven steps.

Target 20 Roll: use 1.5 x difference as modifier; one side "attacks" other at 10 + d20 + modifier, no level bonus.

• PRO - looks like a save or attack roll; modifier shifts odds in equal steps; granularity closer to that of original rule.
• CON - unusual multiplier to get modifier; need to remember +10 adjustment or record it on reference sheet.

So, which seems easier?