Comment entries are titled with "on <post title>". Which means that,
even in the feed, it is easy to know which entry is being commented.
That basically destroys the complaint you have about feeds #2 and #4.
I believe that you are completely forgetting that an Atom feed does
not exist by itself - its primary purpose is to be consumed by a
program (generally a feed aggregator). In that context, here are
usecases that I have for each of Habari's default feeds.
> 1. Page/slugs (<site>/atom/<pagenum>)
No need to explain.
> 2. All comments (<site>/atom/comments)
- I am the site owner, and I want to know when one of the posts is
commentated - I could even have software that pings me automatically
when a feed is updated - in which case, having posts in feed#2 would
be an inconvenience. And because every comment title in the Atom feed
bears the post's title, I always know for which post the comment was.
- I add it to feed#1 and I now have both posts and comments in my
aggregator. Because the posts and comments are in separate feeds, I
can organize each of them in different folders (when I see 1000+ new
entries in my aggregator, I can see that 950 of them are comments and
> 3. A single entry (<site>/<slug>/atom)
If I have not subscribed to feed#1, I may want to subscribe to feed#3
so that I have it in my feed aggregator, and I can either keep it
alone (I'm on Google Reader, so the articles that are on my Google
Reader constitute a kind of Blogs archive for me), or I can put feed#4
in my aggregator at the same time. While that feed is the one whose
utility is most debatable, it is in fact required if you are to have a
> 4. A single entry's comments (<site>/<slug>/atom/comments)
I add it to either feed#1 or feed#3 and I have all comments about a
precise blog post in my aggregator - I let the other feed (either 1 or
3) have the corresponding blog entry.
In addition to lack of flexibility, I see an enormous downside with
your feeds (feed#1+2, feed#3+4), that would prevent me from ever using
them: If there are too many comments, the post entries will be pushed
out of feed#1+2 much sooner than when feed#1 is alone - it will be
easy for an aggregator to miss your entries because people made many
comments. By keeping the feed#1 separate, I insure that, at least,
even if many people comment very quickly, they should still get all of
my blog entries (they may miss comments though). And in feed#3+4,
unless you're willing to keep the entry and an unlimited number of
comments, the entry will eventually be pushed out - something that
cannot happen if you keep feed#3 separate.
In short, the small convenience that such feeds bring (I don't have to
subscribe to two feeds if I want to have it and its comments on my
feed aggregator) does not make up for the inherent drawbacks. Now that
I think of it, the drawbacks are so big that I would not be in favor
of putting them as possible feed options in Habari's default feed
plugin. It looks like a neat idea at first, and only later does one
realize that it is a trap.