Do we have any statistics giving an idea of how many people follow new questions on tags via RSS feeds? We have some sort of a proxy for this information via the number of followers shown in the tag-bubble, but this feature is, I guess, probably not used so much by somewhat casual vistors to SX sites, while looking for RSS feeds is a pretty well-established behaviour.
I ask this following the discussion of an answer I gave to a question, Do we want discipline-specific tags? about the value of tags for professional specialisations on tex.sx,
