Hi,
First of all, the specification committee may recommend, but they are not in a position to mandate anything about how the project structure themselves. I guess the PMC could set some requirements in order to let a project pass a review, but in this case, we are not.
spec + api in one repo
The reasoning for keeping spec+api in the same repository is for simplicity and assuming that you would always release them together.
spec + api in separate repos
The reasoning for splitting spec and api in two repositories is for flexibility and assuming that you would release patch updates (service releases) separately.
While it would certainly be nice to have the same structure in all the specification projects, I don't think we would reach any consensus on this now and don't see it as important enough to spend time convincing the other half about the benefits of one way over the other.
So, pick whatever way you feel comfortable with. It can always be changed later.
The TCK needs to go in a separate repository since it has a different license
Ivar