The clear disadvantage of buying a map from Garmin which is other than for the 'OEM' map area originally loaded is that you will not get any additional files such as JCV for your unit. The Garmin server recognizes the origin your unit [i.e. it's 'localization'] by it's unique Unit ID and limits the download to the mapping data on a quite expensive 'one-time basis' only. This is what Garmin state under the 'Download Requirements' of the Requirements tab for the EU CN as well as all other such CNs purchased 'out of oem area':
Please note, these full-version maps do not contain premium content such as junction view or 3-D buildings and terrain. These features only are available on the preloaded maps within your device or through a specific update for the mapping region of your device.
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