10 levels sounds like a recipe for analysis paralysis, but maybe that's just me? I find it difficult to choose between 3 levels for a different system, so 10 levels seems extreme.
How about using a floating point between 0 and 3 (including null of course)? Thus, we could allow people to use integers like 1, 2, 3, but also allow high granularity like 2.3, 2.4, etc.
This way, we cater to different audiences and different needs.
That said, I tend to prefer "KISS" (keep it simple, stupid), so we could also just use strings like "low", "medium", "high" - this would avoid any confusion as to whether 0 or 3 is the 'higher' value, but with the disadvantage of forcing English into every rule, regardless of language.