There are roms that take up 4 GB, you know (Resident Evil, for example). And don't forget that 4 GB means ~3.7/3.8 GB... Maybe if you trim them. But then you'd be left with just one game... Nah, they're pretty cheap nowadays. 8-16 GB is more than fine. Trust me, you don't wanna have to switch between more than 4-5 games. The waiting is extremely painful.
A better alternative would be buying a larger SD card instead of a larger microSD (O3DS uses the old SD type), and using that for installing and running CIA games from Pasta CFW instead of constantly having to switch them on the Sky3DS and worrying about save game files, etc. The 2 GB card is more than enough for Cubic Ninja (needed for running Pasta CFW).
modmymoto anyone?
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