Reading this means CoreDNS has done its job!
…And CoreDNS is live:
% dig @linode.atoom.net TXT CH version.bind +short "CoreDNS"
This is quite nice, because it allows me test it properly with 3rd party tools, like zonemaster. That turned up one issue with EDNS which needs fixing. It would also be nice to have an automatic update and reloading of zones (after a signal).
The EDNS stuff will be fixed real soon ™. The other stuff is less important. I will now also focus on performance, testing and fixing issue with the current set of middleware. (Although super awesome middleware is welcome!)