i have had a deerhound x best dog i have had so far all round, got a collie x whip x grey spot on for rabbits, my pup is a sal x grey 7months so done nothing yet apart from a few day time rabbits but for me if you add deer or sal to the mix just makes the dog stronger, have seen pure greys with really high pray drive and take all quarry, but they burn out quick. just my opinion