Why does it have to be for either. Smartness in one and killing in the other. In theory that combination should work. Iv seen a good collie bull grey. Not speaking for all collie bull crosses but you can only know what you see.
What would you class a good cross? Saying most cross have them in most lurchers out there. I have a friend that hunts one it does everything he's asked of and more.
Iv a dog pup here around 18 months was dropped short showing on top of ground a couple of time no interest at all. After reading these I'll give him abit more time few rats maybe get him going see how things go from there?