You definitely want each character to specialize in one ability point type (though getting some Speed too is helpful once you have enough INT, DEX or STR).
I have a dual Lone Wolf party with a cast-everything glass cannon spellcaster and a melee fighter/crafter.
A lot of fights, the melee fighter doesn't do much -- the caster turns the field into a smoking ruin and rains down fire, poison and boulders on enemies who can't see us to do anything about it.
Other times, the caster stuns/freezes/blinds enemies and the melee fighter takes them apart. Still, on average I kind of think a ranger with geomancy would have been a better second character.
