|CR based Individual XP (listed per ECL) uses
the rules in the 3.5 DMG and 3.0 FRCS to determine XP
based on the actual character levels (treated as a minimum of 3),
individual opponent CR's, and the Qty in the party. This grants higher
XP to lower level participants, allowing them to catch up to their
higher level comrades.
||CR based Uniform XP
uses the rules in the 3.0 DMG to determine XP based on Average
Party Level (treated as a minimum of 3), individual opponent CR's, and
the Qty in the Party. Analysis proves this only really works for a
party of four with the same ECL's.
||Difficulty based Individual XP uses the
guidelines that it takes 13 1/3 typical (difficulty factor 0)
encounters to advance a level. However, using this method, differing
level companions will never catch up in either XP or level. In my
opinion, this method adheres most closely to the spirit of the rules.
||Difficulty based Uniform XP uses the guidelines
that 13 1/3 typical encounters to advance a level. However, because
Average Party level is used as a multiplier instead of the individual
character levels, differing level companions will eventually catch up
in level (but not XP).
This is the method I recommended.