Re talking about XP:
There is already a lot of CB (and even SOPW) chatter about what the levels mean, what powers they have, etc. If there are 20 levels, the docs on levels and powers will generate even more confusion and generate more discussion on it into the forseeable future, not just while this proposal is being discussed. (and I don't mean to say that the docs need improvement, people get confused about them even though they're fairly straight-forward now)
Re relative ranking: Ten things are easier to compare to each other than 20 things are. Perhaps other monks are more familiar with the spiritual hierarchy, than I am, but I wouldn't have any immediate idea what the releative position of a beadle, a deacon, and a parson is without looking it up each time. I like being able to click on a person's name in the CB and being able to see an immediatly understandable word to describe their level.
Re another reason I dislike this proposal but forgot to mention the first time: If this is meant to encourage participation, it will fail for lower orders of monks because currently the goal of reaching the highest level is actually obtainable within a reasonable period of time. If newcomers see that it will take them years to reach a high level, there's really not much incentive for them to try. The only group this actually adds incentive for is the 322 saints out of the about 10k users with writeups and about 30k registered users.