The directory where ovi maps stores it maps is also in MyDocs (/cities). So if you want to upload maps (for offline usage) for e.g. whole Europe (source), or the whole world , you will run out of space very quickly.

So better choose a bigger MyDocs if you want to have a lot of maps on your device.

Or could it be, that there is another solution? E.g. a config file to tell ovi maps that the cities directory can be found elsewhere?