I hope you get some real-world experiences reported, but…
Given the common knowledge here of general SmartThings instability, you really should keep in mind that the more Locations you have in one Account, the more likely you are to run into issues.
Even if a large number of Locations are not the actual cause of some eventual problem you experience, it is entirely likely that there will be a problem with your “Account” record for some other random reason.
When SmartThings Support then recommends you reset / delete your Account record, I can assure you that all associated Locations will be blown away, along with all of their connected devices, automations, scenes, routines, rooms, and more.
Yes - That is a very real risk.
If you find ActionTiles useful as a view & control dashboard, you’ll be relieved to know that you can connect any number of Locations from any number of same or different SmartThings Accounts to one or more ActionTiles Accounts.
In other words: For ActionTiles mix & match dashboards, your Devices, Hubs, and Locations don’t have to be all piled, dangerously, into a single SmartThings Account.