As long as they retain the option to disable certain features on a repo, I am wholly in favor of consolidating the development stack into GitHub. Easier to mandate 2FA and other security procedures when your team doesn't have to juggle several sites.

Friendly aside: the expression is "err(s) on the side of..."

Zeit's was the most active spectrum community I was part of, interesting they're the lead tester community for this new GH feature. Spectrum fell between a number of posts, it was never really "chatlike" so it looks they've gone completely in the forum direction with discussions.