You said a grading exam isn't as stressful as competition or combat. My question was simply: Then isn't it a bit of a disservice to make any combative claims if the student never experiences anything close to combat?
Forget the rest, answer the question.
I know this because in the past I've felt my technique was not my best in a grading, and I've watched my students techniques deteriorate at a grading.
The myth of peak performance. Some days you're the windshield and some days you're the bug. If this is a common occurance for students during anything (testing, a particular drill, a particular technique) that would indicate to me that there is a coaching issue that needs to be addressed. (For example, I guarantee the same thing will happen with students that are fatigued.... as an instructor, what does that suggest to you?)
I submit that grading in aikido is so subjective with criteria varying so much among different instructors, different dojos, different organizations, etc... that cross-comparision isn't possible. With such great diversity, all rank is subjective, and however it is awarded (or not) is perfectly fine with me.
Like Erik, I am a heretic with regards to rank (and other issues) ......