Check out my Think Like a Judge article in Zymurgy or the Be Your Own Best Critic article in BYO for tips on assessing your own beer and entering in competitions.
I agree with the "taste it" comments, but keep in mind there is another answer besides A, B, or A+B; it's "none of the above."
If you can't taste the oats, then don't enter it as 23. If the oats make the body seem too big or hurt the crispness of the style, don't enter it as 10a. If it doesn't fit in either, then save yourself some money and don't enter it at all. It sounds like a good beer, but not all good beers have a clear fit in a competition.
Judges in the competition will be judging it against the respective guidelines, so objectively compare it to those.