AAC is the same
I would say it depends on the dog. I haven't seen vids of Steve (assuming you are talking about him) but going on his structure I would think that given any jumping aptitued at all I would try him at his regular height. 26 isn't really all that high. To me its more about weight to articular (joint) surface when looking at impact issues.
Kaiden jumps 16, he is 13 inches tall (the cut off is 12) He is turning 9 this year. I have debated putting him in specials or vets (where he would jump 10) but its not the jumps I am worried about but the frame. I think a typically athletic dog should be able to handle jumps higher than agility courses require and stay sound and happy.
If the dog was heavy (not fat, just very bulky for the size of joints), badly structured, total clutz over jumps or very non confident then I might opt for a lower height.