I thought I'd update the other users here on recent events on Groups.io. Three weeks ago, The-Tech-Zone, a general technology group shifted over to Groups.io. With 196 members, The-Tech-Zone is by far the largest group on Groups.io apart from Updates. Additionally, five groups related to disabilities recently appeared on Groups.io too (Blind-Facebook-Users, BlindChitChat, Dissasociativetalk, BlindTwitterUsers and BlindMentalHealth). Of these five, Blind-Facebook-Users is of particular note with 78 members. I don't have exact details on how these events are related, but I believe The-Tech-Zone has a significant audience of people with disabilities and some of these other groups may have been pre-existing and by shifted over due to either shared mods or mods being members of the Tech-Zone. Regardless of exactly this has occurred, Groups.io is gaining significant traction.
Lest anyone think the the traction was purely related to the disability niche, two unrelated groups: Rant, MusicRequest have reached the 20 user mark, as has my group, future-tech.. I suspect that these groups have been able to reach this size largely because The-tech-zone (and the related disability groups) have brought more people into the Groups.io ecosystem. So those you who attempted to found a group before but found it difficult to get members might want to consider promoting your group again.
It is my understanding that The-Tech-Zone allows you to post that you've created a related group (although I recommend checking the most recent statements on this yourself). I took advantage of this and I gained a few members from this. I suspect that anyone wanting to found a tech or programming group would be able to find people interesting in joining now.