I have two sandisk 8gb cards, both have less than 500MB free space left. They filled with games and videos (one card is mostly videos).
Currently using English Sakura, and have no problems with at all, I can load and play any game and video.
I recall that few months ago, when I was using older firmware some folders could become corrupted for some reason (corrupted while they were in m3 real, not in usb adapter) - after restart I could not enter some folders, it happened few times after playing some games. Nintendo was hanging when I was trying opening such folders, other folders were ok. Under MS Windows directories could be opened with no problems at all, there were no lost clusters/logical errors on the card (checkdisk checked). I could not find a reason why those folders would hang the Nintendo. I've tried deleting all .0/.sav files, defragmenting the card etc but still it was hanging... The only solution was to delete the folder(s), create new one and copy files to card from backup.
I didn't experience such problems since I upgraded to Sakura firmware, don't know if they fixed it, or maybe was just lucky.
I don't know if it helps or not but you might try reformatting your card to FAT32 (with default settings) and try again. Also, make sure that your USB adapter does not screw up the card, like adapter which comes with M3 Real often screws up logical structure of the file system, so even if card looks like properly formatted it will have some logical errors and would not work properly. So, if you use USB adapter which came with M3 Real - you'd better get another one.
P.S. by the way, in older firmware max number of files per folder was 128 (you would not be able to open files higher in position than 128), in Sakura I've tried it with approx 180 files per folder and all of them worked, so even if there is a limit - it's higher than in older firmware.
Currently using English Sakura, and have no problems with at all, I can load and play any game and video.
I recall that few months ago, when I was using older firmware some folders could become corrupted for some reason (corrupted while they were in m3 real, not in usb adapter) - after restart I could not enter some folders, it happened few times after playing some games. Nintendo was hanging when I was trying opening such folders, other folders were ok. Under MS Windows directories could be opened with no problems at all, there were no lost clusters/logical errors on the card (checkdisk checked). I could not find a reason why those folders would hang the Nintendo. I've tried deleting all .0/.sav files, defragmenting the card etc but still it was hanging... The only solution was to delete the folder(s), create new one and copy files to card from backup.
I didn't experience such problems since I upgraded to Sakura firmware, don't know if they fixed it, or maybe was just lucky.
I don't know if it helps or not but you might try reformatting your card to FAT32 (with default settings) and try again. Also, make sure that your USB adapter does not screw up the card, like adapter which comes with M3 Real often screws up logical structure of the file system, so even if card looks like properly formatted it will have some logical errors and would not work properly. So, if you use USB adapter which came with M3 Real - you'd better get another one.
P.S. by the way, in older firmware max number of files per folder was 128 (you would not be able to open files higher in position than 128), in Sakura I've tried it with approx 180 files per folder and all of them worked, so even if there is a limit - it's higher than in older firmware.