I believe lots of people, including me, have used a Zipp Super9 disc with no issues in the SC, and Zipp lists the brake track width as about 26.5mm. Walker lists as 25mm? I'd assume no issue.
EDIT - When Walker lists width as 25mm, hard to tell if they are talking about internal width, or brake track width. If that was internal width, clearance might be tight. Best confirm with them!
EDIT - When Walker lists width as 25mm, hard to tell if they are talking about internal width, or brake track width. If that was internal width, clearance might be tight. Best confirm with them!