Well that's the problem-unlike cache sizes where you can specify that a large is say 20 liters, a cache rating is an opinion. And like I pointed out subjective. An LPC is so easy that most of us hate them but to a new cacher it might take 5 visits to find it. Plus unfortunately only the CO/OP knows where the caches is going so we can only guestimate an appropriate rating based on what we perceive the cache location is like.
So to the OP go with the official one Cerberus linked to.
Which is the same one I posted.
Thanks to all who gave me info on properly rating my underwater cache. With this new info, I think I'm going with a 5/3.