I've found many "pure" breeds to be regrettably diminished, they look like the books say but they pay for it in some way. Shorter lifespans, health problems, mental problems, etc.

Out-crossing a purebred with something from a different style of dog can often produce much healthier pups than either parent. Great Danes and Collie make 3/4 sized, slightly skinny dane-like dogs that are shockingly robust and energetic and can live to 16+ in my experience (and that's as active working outdoor dogs).