If anyone else is thinking about switching from mailing list subscriptions to the RSS feeds, forget it. At least for now. RootsWeb says the feeds are an experiment. I got this response after contacting the Help Desk.
I wrote them because I was finding that some list admins didn't know that RSS feeds had been created, some have no clue about RSS, and some are reluctant to add users to the accept list. While the first two reasons are understandable — RSS is still fairly new — I do not get the reluctance of some admins to add users to their accept list. All it does is create more work for them. As far as I'm concerned, they can remain in the dark about RSS. The existence of the feeds doesn't have anything to do with them or the list.
If RootsWeb scraps the RSS feeds, for whatever reason, I'll have to redo my subscriptions. Fun! I'm now wishing they hadn't made the feeds public.