does LW's furry-to-brony ratio fall within that range, or outside it?

So, the ratio might have problems when people fall in both groups; looking at the Brony Herd Census it looks like 17% of respondents were furries, which makes the 10 to 1 estimate calculated other ways seem less likely. (I think most of the estimates I saw for furries predated MLP growing, and it seems likely that the communities grow off each other.)