The Confluence instance wide RSS feed seems to accumulate all kinds of changes (including added pages and updated pages) for all spaces, whereas the per space feeds have 3 individual feeds which categorize the changes into "added pages", "updated pages", and "commented pages".

Personally I'd like a feed per space which aggregates all these 3 types of updates. With a feed like that I wouldn't use the three others at all. But I have no idea how others feel about this, so I can't tell whether the three space feeds should be replaced by a single one or if it should just be an additional feed.