I agree with this 100% but to keep them at a truely high level for very long at all is almost impossible. A year or two is the most you will ever get out of any dog. But.......like I always say, anybody is welcome to prove me wrong at any time.
What I ment to say is DOGS not dog ,in the sence of keeping a line / strain, breed at a high level.
But after reading what you wrote I dont agree, Cully,Teddy myself off the top of my head have all kept multiple breeds well over the 1-2 year mark at a high level.