UA still favors multiple realms. Lets say you are in rank 5 on a weak realm. In UA, you will still get slightly more rewards than you did before. However, if you moved to a stronger realm, you will get barely any rewards if you cannot make it in the top 10. Hence, its better for you to stay in your weak realm. If 3-realm server has balanced realms, UA will nearly benefit everyone compared to original arena in terms of rewards.