if you want to have a lot of room for saves then use uLE and a USB stick. you can backup saves to the USB then move them back when you need them.
the major problem with a lot of the Chinese cards is the read/write speeds. FMCB does not work because it takes too long to get the info off the card that it times out before it has finished reading the card and continues to boot as if the card was not there.
some cards that say they are 64Mb are not they can be smaller cards with compression on them to look like a bigger card. i had a 64Mb card that worked with FMCB 3 or 4 times but after that it wouldn't boot at all. all data was corrupted . i used MC Annihillator
only to find the card was only 8Mb and even though it formatted it never worked properly again. so just a warning if you are going to try the bigger cards then have a backup of the saves in case the worst happens.