Hi there,
I'm asking for help before I try to download a (SanDisk Extreme) CF card to my Retina MacBook Pro, because when I tried the same thing two months ago with a Sony SxS card, also attached via Thunderbolt, it caused a system crash and I had to reinstall everything, including my OS.
I haven't used this card reader for a couple years—back then it worked just fine, but it was a different laptop (an older MBP) running a different OS (Mountain Lion I think). I'm now running Yosemite, on a newer MBP.
So... am I safe doing this?
Do I need some Canon software first?
Thanks so much for any advice.
I have a shoot tomorrow and have to either get this card reader working, or I'll have to buy another CF card, which I really don't want to do.
Regards,
Malcolm

Sony SxS and CF card readers are two very different things, especially if you are using a Thunderbolt SxS reader (which I assume is a Sonnet Tech Echo or Qio). CF should work just fine without having to install zero drivers, while SxS requires two different sets for the Thunderbolt readers. I would assume if you had a crash so intense that it wiped out your OS, that you simply installed versions for the wrong OS. I have done SxS Echo Express offloads lots of times with zero issues.

Thanks so much, Gary.
As you predicted, I had no problems connecting my CF card reader—that all worked out nicely.
I will make sure to update whatever needs to be updated before trying anything again with my SxS cards.
Best Regards,
Malcolm