And even if the RSS feeds are not used a lot by the majority of the audience, I wouldn't be surprised if it helped bring in other audiences. I feel like RSS users are more likely power users and may be more a bit more interested in the site than most users.

I personally know that a lot of the RSS feeds I am subscribed to I also end up sharing articles with friends. I see these articles early and quick and help create early discussion about them and comment early on them often first. I feel like overall RSS feed users may not directly look hugely beneficial to a site, but can have other impacts hard to track.