Mini SD Cards are hard to come by and are - as far as I know - no longer produced. So the chances of getting a "fake" card should virtually be 0.
I always recommend getting a brand name card like san disk, Kingston, etc. and to avoid any off-brand/no-name cards. Size wise, 2Gb is the largest that the supercard mini sd supports but I don't think miniSD cards ever came in SDHC format so 2Gb should be the largest you can get anyways.
alternatively you could try using a microSD to MiniSD converter, but these are tricky. I have one that works fine with mi 2Gb MicroSD and one that doesn't work at all. So they might be a hit and miss. You should also note that with such an adapter 2Gb is still the largest size you can use, MicroSDs of that size might not be easy to come by either.
The Supercard mini seems to have slow flash storage or maybe it even directly accesses the SD card so loading a game suffers from considerable slowdowns. Depending on the game, this might make them unplayable.
all in all, i'd say the ez-flash IV would have been a better choice, no slowdowns, easier to find compatible SD cards, etc.
