Here's a couple observations:
I've tried the app with a couple test users, I don't see the publish_actions permission come up. I'll assume you are correct though, but you might want to make sure that this is the case. For answering I'll assume that you are correct. Asking for only publish_actions is the way to go, I have metrics on it, but I can prove it mathematically / logically, so I don't have to use stats for it....
- publish_stream always gets asked on the extended permissions page
- publish_actions will get asked on the first page, except if you ask for publish_stream too, in which case both show up in extended permissions
- when you make a story post, you don't get to decide under which permission to do it, Facebook just check to make sure that you've the proper permissions.
- if a user has given publish_stream, then the stories are visible to the posting user in their newsfeed.
- if a user has publish_actions, then that story is NOT visible to the posting user in their newsfeed, but their friends can see it, and they can see it on their timeline.
- if you have both perms for a user, then when you make a post on behalf of that user, Facebook will make it in the style of a publish_action story, so the posting user won't see it. So to a practical effect, it is not really useful to have publish_stream if you already have publish_actions.
So, given the above observations about Facebook and applying it to your case, because you are asking for both perms then they both are on the extended permissions page. Because you have both perms, when you post a story it is going out in the publish_actions style.
If you look at the funnel, it is:
Current: sign in with FB > regular perms > extended perms > signed in.
Proposed: sign in with FB > regular perms > signed in.
The proposed solution is better because:
- it removes a step in the funnel. You probably have double digit drop off from one step to the next, so that helps dramatically with virality.
- publish_actions moves from extended to regular permissions, so you get that earlier
- you don't lose anything by not having publish_stream, because if you have publish_actions then your story posts are done like publish_actions and not publish_stream, so it is a perm that you aren't really using or need.
The con of the proposal is that publish actions requires a token, and the token expires after 60 days if the user doesn't come back. Internally I've found that stale users like that aren't that useful as a viral channel anyway. So it isn't really much of a con.