In this lurcher saturated world, there are far more examples of bad collie brain than good IMO because though I am certainly getting a bit better with age, harnessing that brain right ain't every ones forte and for the layman, most collie crosses are a damn sight harder to handle than other crosses. They can be simply too much dog!
Edited to add, personally, I'd rather have, some of the other good points from these crosses, feet, stamina, coat, frame and bone. To me the collie brings more to the table than brain alone when crossed with your speed machines.
Oh yer, Stabs and Tomo are dead rig