Fwiw, the larger 9.7 inch iPads will dissipate heat better than the Minis. When you get to using a heavy processor autonomous app like Autopilot, you might wish you had gone to a better device if it overheats, processor speed slows down to compensate, and then may break up video in warmer climates. Autopilot's preference is the iPad Pro 9.7 + Cellular over the iPad
Air 2 + Cellular and they both will barely fit into the stock RC controller clamp by a millimeter. Mine fits into the hard case's foam area made for it too.
My big fingers have enough issues with smaller screen icons that I need to use a stylus. For me, bigger is better although being bulkier. Some sliders in GO, color temperature for one, are almost impossible for me to set without the stylus as my index finger pretty much covers the entire slider area to work it. Even using it with Autopilot, I often have to "roll the stylus" to move waypoints a bit on the iPad
Air 2 9.7" screen. My finger will never work there.
I think Apple is supposed to come out with some new models soon. Likely more speed, etc. Maybe in a month or two.