https://help.geni.com/hc/en-us/articles/229706367-What-are-the-bene...
Probably the major two advantages of Geni Pro are
1) you can SEE the matches to other profiles on Geni that Geni suggests, instead of just getting an Ad for Pro
(the left-hand box - the blue box; the suggested Record Matches (brown box) and Smart Matches (green box) require both Geni Pro and MyHeritage Data Subscription)
and
2) if there is a problem, you can submit a ticket for Help (go to Help to do that).
I think also, you have to be a Pro to "break the Tree" - ie disconnect a profile that is not connected otherwise to the Tree.
No idea what "unions center" is. No idea what those three profiles are there to show or ask or whatever.
Yes, Geni is just about building the Tree and uploading photos and documents to the Profiles and filling in information on them, etc.
If building the Tree and helping to Document those on it are not your idea of "Fun", then no, probably no "fun thing" connected to being a Pro.
One does not "join" a profile.
For those that are MPs and have over 100 managers already, and a Curator, cannot think why one would want to add oneself as a manager (if that was what you meant).
Anyone can Follow any Public or Master Profile (or Private Profile they in Max Family, or managed by someone in Max Family) - just click "Follow" in box to Upper Right of the Profile - then you should be notified of changes to that profile.
Being Pro makes no difference when it comes to being a Manager of a Profile or to Following a Profile.