As for capacity, I’d go for 64Gb and get a handful of them. While 128 and 256Gb may hold far more and only require a single card for a day out, leaving plenty of extra space, if that goes wrong, and I guarantee it will, just when you least expect it, you’ll end up losing so much more, then if you spread the load over a larger number of smaller capacity cards. Failures aside though, I see no real benefit between the Extreme and Extreme Pro to be honest, certainly not, if like me, you own a Mini 2 and offload all your footage, onto a PC, using a card reader. I have been using Sandisk Extreme cards for years, both in my DSLR and now in my Mini 2…The Extreme is plenty fast enough for me
and as Trailblazer points out, 64Gb Extreme Pro cards are selling at a very reasonable price at the moment and you can never have enough of them in my book. Not so many years ago, you could pay 3-4 times that for half the capacity.