I think Groups.io would prove to be the smoothest transition for me, requiring no new app and supporting my no-email preference and allowing others to choose a digest, and the rest to just change the address for sending. The founder is getting hammered with requests for new groups right now, but the free tier looks like it would accommodate most everything that we did before (while requiring a limit to the attachments). I do believe that transfer of the archive is something only done for a pay tier, though.

Constantine