i prefer brains to speed, as has already been said in most cases the more speed you get the less stamina you get. i like to know in the back of my mind that you have a dog thats got it in the tank for those one off nights when you turn up to the ground you have chose to lamp and everything is just right the weathers spot on and the quarry is out. personally i like to take advantages of those nights and push my dog and see what he can do.