Can you be more specific? Existing update "infrastructure" as I understand it consists of updating a file so that when you hit its URL you get the contents of the new filter list instead of the old one. RSS is the same mechanism—you rewrite the contents of /feed.xml, for example—but for no net benefit—it just adds a layer of indirection, plus you deal with "XML" containers. That is, the format looks like XML and even pretends to be XML but very well may not be, due to the legacy of RSS.