I really like this system -- you've thought it out well, and it removes most of the lacunae that other fannish rating systems seem to have. It's simple, logical, and works in plain English rather than in abbreviations. I despair of its ever catching on because of the usual fandom = cat herding problem, and I'd hesitate to use it myself because I'd have to link to this post every time, etc. But that's a hesitation, not an outright rejection, because I do really like this.