I have a similar pair. My gal-dog at 58 pounds is a little jet rocket. My big boy at 91 lbs is a tank. He has his burst of speed, she has more endurance for a long run.I do not do Ipo but Max is lighter built even though he is a big fit dog 85lbs and quite an athlete. Max was always very agile even as a pup. Very coordinated. I think it’s why he can stop on a dime catch a blueberry in the dark at quite distance. We have woods in our backyard and he is dodging around those trees every day at full speeds. Karat our male had weighed about 90lb plus he was really stocky he had a really long back. I would not describe him as agile and fast but a very powerful brick house.