@luckow thanks for your input 🙂
In part just so everything in one place and so I just have to manage, maintain, update etc one server instead of several servers.
But also because e.g.
I've got an instance of PeerTube on one of the smaller VPSs (it's bridport.tv so makes sense to have it on my.bridport.coop where I've got all the Bridport stuff), but I've realised that it really needs a lot more power than that server has.
I'd also like to give access to some of the apps of got on my.uniteddiversity.coop to all the people on my.bridport.coop - at present this would mean them creating another account and then not having the same credentials for both (although to be fair most of the apps currently on my.bridport.coop aren't LDAP enabled anyway, either because they don't have it - like Discourse - or because it doesn't really suit the use case - public instances of PeerTube, Mastodon, Pixelfed).
I think quite a few of the apps would likely benefit for the increased power the dedicated server would have.
The issues you've highlighted wouldn't be that big an issue for me because I think I'm currently the only person/ name who is on all of them so there aren't two Jane Does (but there would be if I started saying "sign-up over on my.uniteddiversity.coop so I can give you access to our shared x too".
The biggest issue would be getting the handful of people actively using some of the other Cloudrons over onto the One Big Cloudron, but currently the numbers of people I'm talking about would be manageable (but this gets harder as more people start joining the other secondary Cloudrons).