and trust me when I say you are way better off with the advantages of human charisma then the advantage of svirf earth elemental.
for svirfs only, regardless of any edges, their earth elementals do 133% damage of a normal earth elemental and they have dam redux that I would estimate between 30% and 40% and about twice as much hp as a normal elemental (they can take a ludacris beating basically and its a super rare situation where any other elemental can do more damage then them even when that elemental is exploiting a vuln and the earth is not)