I'm sure it's worth a feat, but what I'm saying is that I'm not sure it needs Leadership as the first tier in the chain. Any prereq that could reasonable impair a character by narrowing the field of choices would do.
Intellectual Leader [General]
Prerequisites: Cha 11+, Int 13+, Any Two Skill Focus feats, Character Level 6+
You gain followers and cohorts as if you had the Leadership feat, except that your Charisma-based Leadership statistics are computed using your Intelligence bonus instead.
Normal: The Leadership feat is based largely upon Charisma.
Survivor Guru [General]
Prerequisites: Cha 11+, Con 13+, Endurance, Survival 8 ranks, Character Level 6+
You gain followers and cohorts as if you had the Leadership feat, except that your Charisma-based Leadership statistics are computed using your Consititution bonus instead.
Normal: The Leadership feat is based largely upon Charisma.
And so on...