All you can do is try it out.
It's worth formatting the card before you load the .map file. This ensures the file is written in contiguous chunks to the start of the card which should help the Nanocom read the map file cleanly.
It's also been suggested that you should save the .map file direct from your email program to the sdcard rather than copying from you hard drive. I haven't tred this personally but I have it on good authority that this dramatically improves the odds of a successfully uploading a .map file.
cheers
Paul

