Well put, be as thorough and clear as you can when explaining your point of view, and have lots of documented examples to demonstrate your points and your scoring. Try to give as many (if not more) examples of their positive attributes as their negative ones. Good luck!
don't stress it. it doesn't matter. even if you write a totally fake, crap review, if they think you're outstanding, that's what you'll get. last year, i got an O, and i just copied and pasted my last leadership status in there. year before, got an ex, just put random core roles. it's one big colossal waste of time when your score is predetermined.