The reason I'm interested in RSS is for email updates. On a previous version of the Carolyn Carter site, I was using plain-old posts for performances. This led to problems with clearly showing concert dates and locations, as well as grouping old performances by performance date (not post date) in the archive. Your plug-in was the answer to all these problems.
However, the one other feature I had with the old system was a way to automatically send emails of new performances to subscribed fans using the Jetpack plug-in's feature for emailing posts. Since MF Gig Calendar doesn't use plain-old posts, the Jetpack approach no longer works. However, MailChimp has a nice feature for doing email campaigns based on RSS feed. The emails it produces are formatted better, so I was looking forward to making the switch - once there is a working RSS feed. :-)
If you haven't encountered it yet, there is an excellent online RSS validator to show you the errors.