The device type changes the keys that can be directly assigned in an upgrade. IIRC, the VCR type has the most keys. It is arbitrary which device type you choose, but the choice in KM or RM must match what is in IR. For Volume Punch Through (VPT) to work on the device key the device type must match the device key. (However you can always key move the appropriate V+/-/mute to the non-native device.)