I would not move maps to a SD card if it can be avoided. About once every 1-2 years (unpredictable) I have to remove and clean the SD card contacts on a high quality device and card. If this happens during a tour I would need to remove the nav from the bike, remove the case, remove the SD card, clean and then reverse the process. And this is assuming I am in a clean location to perform such surgery. No thanks. SD cards are unreliable in my opinion.
Ping me if you really want to do that and I will try to help.
