One additional question. How do you usually use Ipad when modeling? Do you hold with your hand/lap or do you still have on table supported by some kind of stand or Ipad cover?
I just visited an electronic store I was surprised how big the 12.9 Ipad Pro is. There is definitely a huge difference between the working are when comparing 12.9 vs. 10.5 / 11 / 9.7 sizes but I would assume that these are used in different manner also.