Erik - I also went for Sandisk Extreme Pro 32s for my 1DX (4 of them). Two of mine are branded UDMA 7, the other 2 UDMA 6.
I wish I could find the UDMA 7 ones.
I figure I'll be buying cards again so I can get the faster UDMA 7 stuff later when it's a bit cheaper.
These two new ones along with what I already have should keep the cameras happy for a while.