I really enjoy agility, and I know a LOT of people with border collies. There is NO WAY I'd ever own one, lol! Those are dogs that are clearly, clearly meant to work all day. I simply couldn't provide them the life they need. I really love Aussies, too...I might be able to give one what they need...maybe. But again, they really are bred for a lifestyle that many people can't provide. I see sooooooo many people with those breeds who really struggle to meet their needs. I admire them tremendously but I don't think I could do it.
They sure do excel at the sport, though!
There aren't nearly as many Dobes running agility around here. It seems like people do seem to get breeds specifically for the sport, sometimes, and that often isn't a Dobe. We have some, and some that are super talented, but they aren't as common. Then again, we simply don't have tons and tons of Dobermans in MN, either.
I couldn't deal with a Border Collie--they seem to be another entire notch above Aussies for needing to have 'work'--of some sort, all time. And if you don't provide it they'll find something for themselves to do and mostly you won't like the results.
I think my Aussie was pretty easily satisfied (he was working line on his dams side and show line on the sires side, first generation that were accepted into full registration by the AKC and was dual registered AKC/ASCA.) About the time he had hit adulthood I had started to acquire a small herd of Dobes for him to deal with. It was pretty hilarious to watch him in the back yard trying to herd the Dobes--he wanted them off the fence and they wanted to be near the fence so they could at least hear what was going on (tall wood fence that none of them could see through. He also tried to herd the cats in the house. You've heard the expression--"useless as trying to herd cats"? I saw it in action--there were three cats and he could never even manage two of them going where he thought they should.
Washington State, Oregon and Northern California are and have been for many years the treasure trove of good Dobe breeders, many of whom have always put performance titles on their dogs--when Agility came along a lot of those folk jumped right in to compete in that venue as well as Obedience (and Tracking--and Schutzen--if and when the GSD folk would let them train and compete).
Both Border Collies and Aussies started out around here as classic 'farm' dogs--they weren't house dogs and they weren't pets. They lived in the barn and were fed out there. Aussies seem to have made the transition to house dogs/pets somewhat better than the Border Collies did. And I don't think they are ever as 'driven' as the Borders.
And they seem to be a good match for Dobes--for energy and basic intellegence and for having good 'off switches'.
I miss my Aussie--he provided a different sort of companionship than the Dobes did--I've thought about getting an Aussie in my old age but I would never survive raising a puppy--they are increments of worse and more bizarre behavior than Dobe puppies if you can believe that.
There's no doubt about it--Borders, Aussies and Dobes can really shine in the Agility rings.