Frankly, I think ff.net and AO3 are much of a muchness if you're trying to figure out numbers for Yuletide. They've both got their pros and cons. I have do admit I prefer ff.net's search, but the fact they quarentine off the crossovers and having to remember to make sure you've included the mature rated fics is a pain. AO3 lumping everything together is good, but dear lord the tags (and why does almost every section have at least one 100 crossover?!)