locked Announcement in other moderator groups?
Are you interested in announcing groups.io, and this beta group, in the other moderator groups on Yahoo? If you'd rather that happen "organically" there's enough overlap in membership of these groups that I'm somewhat surprised that there's been no mention of the EL-M conversations in the others yet.
As a moderator for both YGOG and GMF I can tell you that such an announcement would be welcome. Even though the focus of those groups is strictly on Yahoo Groups, we have had discussion threads in both groups discussing the merits of other services. I consider discussions of relative merits to be on-topic, but getting into the "how-to" of the other services to be off-topic.
That's unlike EL-M and ListHelp, whose subject includes all mailing list systems. I don't know about FEM, their group description sounds specific to Yahoo Groups, but they are old enough to be named For Egroup Moderators so you could always ask the moderators about it.
There is also modsandmembers, whose mission was once to stop an earlier rollout of a major revision to Yahoo Groups, and which took up the fight again with the roll-out of Neo. They are currently going through some existential angst, as it appears the fight againts Neo is definitively lost. I know they and their members are very interested in Yahoo alternatives.