Regarding the subscription options:

I was very pleased to find GIO.  I joined “egroups” in the early 2000s which was free and that worked perfectly.  It then became Yahoo groups and over a period disintegrated. 

After  the way Yahoo sabotaged the groups, I am sceptical of anything that’s free.  So, I am prepared to pay for a good service and plumbed for the level I needed, i.e. premium as it has the facilities I need to manage my group effectively.

I have to agree that $20.00 a month is probably more than I’d wish to pay.

So rather than introduce an intermediate subscription do away with the free version and introduce free trials and reduce the cost of the premium with perhaps storage options, the more you want, the more you pay. 

I only intend my members to post messages and perhaps the occasional file so can keep storage to a minimum.  You can also manage your storage by deleting older files.

If you have a free platform, there will be those who never move away from it.

But there is on business principle that no one can get away from, to be profitable , you have to make a charge for services.

John Wirtz