Looking again at the third image in my original post, the summation name in the Gradebook setup view could also be used and would provide consistency between Gradebook setup and Single view.
A category named "Assignments" has the category total named "Assignments total", and a Quizzes category is listed as "Quizzes total".
I still like the idea of having some kind of character used to differentiate from grade items. Having this help catch the eye of the grader to signal that maybe he/she should think twice before editing this in Single view. Something like:
Categoryname [total]
How does the following strike folks?:
Assignments [total]
Quizzes [total]