IMHO, the Willpower aspect should be a function of Charisma, which already states that it is Force of Personality.
If that change were made, then, I've also proposed that saves operate thusly:
* FORT: Str or Con
* REF : Dex or Wis
* WILL: Int or Cha
Str for FORT just because I think it makes great sense that a hulking creature should be able to withstand a lot of abuse.
Wis for REF due to the Intuition aspect.
Int or Cha for WILL because if you realise you are being tempted/controlled it ought to count for something, and if you are just such a cantankerous cuss your force of personality (Cha) should be able to give you an edge.
I realise that this is similar to 4nother RPG out there, but if I'm not mistaken an earlier version (2nd) used something similar in its Skills and Powers books.
Comments, ideas?