I think it would be nice to have the option to download worlds from both servers every reset, because maybe some people want to look back at the builds they have built in the past (e.g. me).
I suggest you get Litematica mod and save schematics of your builds as I do. That way, you can paste them into your build world and save it forever. I also take a ton of screenshots. And, I don't think you realize how big that map would be to download. Think about every player: their builds, their laggy farms, all the entities they have plus the nether and end realm. That includes parts of the map loaded from players exploring and looking for resources. It would be overwhelming for even the strongest of PCs.
The idea of using Litematica is smart, I haven't thought of that. Also now that I think about all that... I now realise it would be hard to download the whole world of all realms and how bad the lag would be (that would probably crash minecraft). But thank you for looking at my suggestion
