Short question: Is there a technical difference (under the hood) between calls via ClientRpc, ServerRpc and the new - unversal Rpc [SendTo…]?
Does it make sense to redesign the client-server logic if the game is written on legacy rpc? Will it not cause problems in the future?
In regards to future problems, it shouldn’t cause any issues. Under the hood, it is definitely a bit different and provides more flexibility. However, since you can mix-match RPCs if you determine at some point you would like to only convert some of your ClientRpc or ServerRpc RPCs then you can selectively update those.