I have both the iPad Air 2 and the iPad mini 2, I use the mini in flight as it sits nicely in the Cessna and I keep the full size iPad in the side pocket as a backup. I upgraded from the original iPad and iPad mini 1 as I found ozRunways was getting a little slow for my liking. The A8 (and A7 in the mini) processor run ozRunways very nicely indeed! I also have a couple of battery packs that I keep close by as backup power just in case.
Oh, I almost forgot, both iPads have 4G with Telstra's new 5GB for $50 for 365 days. I found hot spotting was a pain at times and with the ozRunways traffic it seems a relatively cheap way of staying connected.