Reliable data about RSS usage?

Dave and a bunch of folks have been fighting out the question of how to take the next step forward for RSS. This is an important fight, but I have a different question: how big is the RSS market?

Dave has a good idea about the market for producers and consumers of RSS feeds from a tools perspective. But how many websites are out there actually producing RSS feeds? How do they break down by number of unique users–how many 1000 pound sites like the BBC produce RSS to increase their reach? Same questions apply for other syndication formats, too–like the New York Times’ custom headlines format.

Another question: Are websites that have to make a choice to adopt the technology (i.e. RSS syndication doesn’t come from their backend software for free, as it does in Manila, Radio, or Movable Type) doing so to extend the number of people who read their content–simply to grow traffic? Or do they find value in the contributions of people who consume their RSS feeds and comment on them?

Days like this, I wish I were totally self directed and could spin the cycles on figuring this out. But I’m hoping someone out there whose business is in RSS has actually done this. What does the market for RSS generation look like? I’ll be blogging a bit about this for a few days.