By acting as you do, we may end up in a huge amount of feeds being sent on
the wire to clients which believe the feed has actually changed in its
content when it has changed only in one meta-data value (that they will
not handle anyway).
Servers don't *have* to change the feed's Last-Modified and ETag values when a comment count changes. They are free to respond 304 to a conditional GET, even if the count has changed.
Hugh
