The question starts by the observation that all the Sandisk in the "Tested Media List" are with a "J" in the 3 digits final code of the parts# but what i can find on Amazon (Italy) is with a "G".
So I think that the Tested Media List is a bit outdated and maybe the top capacity at the time of the Test was only 32GB.
So I asked about the 512... just for exaggerate, but the same question is valid for 125GB, 256GB and so on. The real meaning between the lines is: "can manage more than 32GB?"
About the smaller capacity and multiple cards, yes I agree with you... but is 1 of the 2 ways (and the 1 don't override the 2): one way is the smaller capacity with multiple back-ups, while the second way is 1 card with non limits room for as many test, mixing versions as you want.
I'm projecting an all-in-one flightcase for the DP32SD + cables + mics + headphones ready to go for field recording in many locations, so one BIG card inside the DP32SD is something I would use in this case.