Thanks for the replies. A shame there appears to be no convenient solution. When I have my new Wii U I'll try copying to a USB device to see if I can make it work. If not, we'll have a little competition about who gets to keep his saves. It's been decided we'll settle it in Smash!
Spending warm summer days indoors
Writing frightening verse
To a buck-toothed girl in Luxembourg
NES, SNES, N64, GC, Wii, WiiU, GB, GBC, GBA, DS, 3DS, Mega Drive, Game Gear, PS1, PS2, PSP, XBOX 360, Atari Lynx