"You may also want to add a category in the bug tracker for RSS/ATOM ."
We're using our official addon names as the set of tracker categories, so it'd be 'core' in this case (as rss is a core service). No one is going to lose that much sleep over it though :).

So these ones seem to be failing for you...

cns_members
cns_forumview
news

Also cns_topicview, but this is a separate issue when opened without a topic filter. We will fix also.

So this is a character set encoding problem. I am running some more tests.

Automated response: Problems with RSS

On all servers, viewing the topic RSS has a possibility of throwing an error if you view it without a particular topic filter (having a filter is the normal case).

On a minority of servers, if the website is not running utf-8, RSS may fail to display correctly if there are non-ASCII characters. This happens when the server hard-sets a utf-8 mime type that Composr has not specified, even though our XML explicitly gives the correct mime type. Our workaround is to also explicitly set the mime-type where the server is inserting the incorrect one.

Your hotfix works. Thank you ^^