After a week or so I can now take stock of the grading and think about what went well and what didn't and how the preparation helped...or not?
My main concern leading up to the day wasmemory recall of the techniques. I've grained long enough to know them to a fair standard (some better than others, granted) so this didn't trouble me so much. I did however *still* get muddled up with the Japanese names and find that there is lag between being asked for a technique and my brain processing it and outputting it as action. So what to do? Well as MattKlein commented, just swot up on techniques and have someone call waza at random. Over and over again. And over some more. This worked quite well and in the grading I was confident that I could manage.
The second issue was not knowing who I would gradewith. As shorinji kempo is based on pair work this can have an effect on performance. Naturally techniques should be able to applied to anyone but in a grading it comforts you to know who your partner is. As it happens when I met mine and we had a chance to go through embu I felt a lot easier. He knew his stuff and was fluid in movement. No problem.
In fact during feedback Mizuno sensei made this very point about grazings. To him a grading is useful as it pressure tests technique. Yes they make allowances for the fact that sometimes we don't have a chance to practice with a partner beforehand but in real self defence you have to make the technique work. And this is grading: making it work under pressure. It's no good asking an adversary on the street to stop and start again "cos I wasn't prepared".
Lastly it's worth mentioning sweat. I know it's notpleasant but on a hot spring day in a packed dojo it becomes an issue when you're trying to apply wrist locks. The answer? Think creatively. Go with the flow of the technique and focus on the outcome (immobilising an opponent, trapping an opponent or maybe throwing). It was trickier but a valuable lesson.