@Kayaker

I use two SanDisk 64gig cards, I never noticed them getting especially hot in practice. Do they get warm when under heavy use like when using them on my 1Dx III? Possibly, but I never pull them out right after heavy shooting. I pull them out when I get home to load the images.

And of course I'm limited in my upload speeds because I don't have USB 3 2.

Not to say I they don't get warm, just my personal experience using them.