When choosing an IC that is definatly something to consider. What good is having the largest and most dense core you can get, if you overheat? I'll give up some efficency to still have good flow to the radiator, but I drive in southern CA. Someone else living in Illinois doesn't have to.
There's a lot of good intercoolers out for Evos, but not all intercoolers are good for every Evo (is that corny or what

).
Bottom line it all comes down to individual needs.