My Ultra 64gb card seems to have died.

the best solution is this

http://www.storagereview.com/samsung_pro_plus_microsd_memory_card_review

as sandisk does not disclose info on what is in their premium SD cards, it seems very unlikely that they contain tier 1 MLC nand. for the said application here, the endurance of MLC and a premium controller are of huge benefit. Both Transcend and Samsung disclose which cards are mlc and which are tlc…for this type of use, mlc ftw