I agree with the others Caine. If a recipe called for Pepsi and someone asked for another soda substitute Coke probably wouldn't be the answer because it's still a cola. Gorgonzola, Roquefort, Stiltson and Blue or Bleu are all members of a simialr family with similar flavors even though each have their own unique qualities.
IMHO I would still recommend the Blue cheese but reduce the amount. Blue as an ingredient is completely different than cutting off a chunk just out of the refridgerator and eating it. Then if they wanted the mildest blue then go with the Gorganzola.
JDP