Funny how true this is, yet mutts SOMETIMES can smash a pure at their own game.
As a young fella I had a lab X, yellow mutt. It was the meanest holder you'd ever see, deer were to easy. Ducks? Her training was we went out opening, I shot ducks she bought them back in perfect condition, and cause it was a river there was some very long retrieves especially when there was several down at once. Could scull a beer better than a lot of guys I know.
Pure breed whippet turned into a stunner once she realized she wasn't gunshy. Best whippet? possibly.
Pip the pure whp, she is now a good solid rabbiter. But fuck, it's been a long road.
Jack, who would know what his breeding is. He's foxy size, jack russel/bullheaded/wanker arrogant cunt attitude and the best rabbit dog there is. He has shown some flash as springers etc up after they have done a block.
Pure or X doesn't matter, what you put into them is FAR more important. Time on the hill at the right time in their development, lots of time right then. And every dogs is different.