@cfleming logbot works by being invited to channels, so you'd have to invite it to your private conversations to log dms. you'd also have to get one of the admins to get you an API key.
on the one hand I think http://slackarchive.io would be great, less work for me, otoh the purpose of this log for me is to take back some control from a platform (Slack) that is out of our hands. Using slackarchive would mean adding another potentially unreliable actor. It's pretty interesting though that they're doing this, as it seems to indicate Slack isn't against this kind of thing. People have told me in the past the logging is against their ToS, although I never managed to find anything in there that mentions logging.
The other question is, will they be able to import our existing archive? It seems on their paid plans they do support import; we'd have to contact them to see if they can work with our raw dumps.
@plexus yeah, from looking at it it looked tricky. I think the IRC gateway seems like a better solution.