[Tobu]

The wikis are git repos as well. Sync them periodically and you're good. Plus it's useful as a backup, because I don't think github archives your reflog.

Issues are normally mirrored to e-mails (caveat: you don't get mail for your own comments), so you can mostly pick up existing threads if your e-mail address book can find the github users involved. If they didn't obscure recipients (at least within an organisation — because I don't think address-book lock-in is worth inconveniencing paying clients), and made an auto self-bcc of your activity, issues would be entirely disaster resistant.