I had a problem with an A-Data 16 GB SDHC card. The partitions got messed up and there was nothing I could do to fix the partitions even after doing everything you've posted (low level formats, trying to repartition and all) it still would only show 11 GBs FAT (the rest was for the ext3 partition but I guessed the card got screwed beyond belief). So it won't always work.

I sent it back in since this card was covered by a lifetime warranty.