Giant Schnauzer here.
If you look at most herding (working dogs) the GS ranks right up there.
They have a bit of a bad rep though. Very willful, and a bite second to a pitbull.
that said, you leave him to gaurd your kids at my place, rest easy.
Rapid speed bursts of 45 mph for 15 seconds means he can cover a lot of ground in a hurry. And at his current weight 125lbs, he still has a year to go before he is filled out completely.
To date he has caught over 11 blue grouse for dinner.
But ya gotta keep them busy or they get real destructive. So far, 1 complete loveseat has been destroyed and 1 wingback chair.