Sounds like a card reader flaw, maybe the card wasn't inserted ideally or maybe the reader had dust in the wrong place. that being said i'd hate to lose 128gigs of photos my largest card is 16gb and is cleared regularly.
I am not concerned so much with the number images on the card because I copy them to the computer regularly. I mainly was concerned with the card failing or as you said the reader could have dust.
I like using the larger cards because I don't HAVE to fill the card (and I never have), it's just nice to know I don't have to be concerned about running out of space and having to put a new card in at the wrong time as I would with a smaller card. It also saves me the need to have additional cards with me and chance misplacing one with images on it. Of course in the K7/K5 I do keep a spare (32gb) in the grip in the event of card failure.
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