Having dedicated devices for each set of IR codes also gives you individual control of how each set of IR codes should be sent from the remote via the Device Properties->RF tab without needing to concern yourself with the RF tab settings for the rest of your devices. The important thing to keep in mind here is that the RF tab settings for a given device only affect any actual IR codes located under that device. If you are linking to an IR code in another device it's the RF tab settings of that other device which govern how the IR code is sent from the remote.