Willy,
Would you mind contacting the admin's of all XMLTV EPG mirrors, and ask how much data they (roughtly) process in a month?
Over June 2017, my server has send out 18.8TB of EPG data, and that is with over a third of the requests denied (requests from Kodi and other non-enigma platforms).
This seems to become serious business, and I think if we want to be able to sustain this growth, we need to think about a more efficient data distribution system, instead of sending large files with repeated and largely unneeded information on every request. If we do that, we probably also have to discuss this with developers from CrossEPG, and maybe other enigma tools out there.
Or do you also want to cater for non-Enigma platforms like Kodi (in which case we have to discuss any new format with them as well).
Let me know your thoughts on this.