I am new to the D750, I am using the same Transcend 32 GB 90 MB/s 600X that I have been using in the D800 & D810, actually thankful for the 2 SD slots versus the SD & CF of the others, never had an issue with these Transcend cards. I am not a believer that bigger is better, The 32's hold 700 + on the D750, and 525 + on the D800 & D810. Since I shoot commercially everyday having more than one shoot on a card is a risk I'm unwilling to take, bad enough if I need to re-shoot anything, I shoot RAW and have never used the jpeg back-up option.
BTW Liking this D750, not as quiet as the D810 but I just waste time and space on the 36 MP Files, if the D700 used the same batteries I would have gone back.
D750 is a nice body except the cables are different than my other bodies which creates a nuisance when always carrying back up cables, dumb move by Nikon in my opinion.
Batteries or cables, pick your pain.