Anyone with a mini *older* than the 5 should upgrade NOW. Since Apple hasn't been updating the Mini very often, it's best to buy one right when it comes out and upgrade every time. It's already been 2.5 years since the Mini 5 was introduced, and the Mini 4 is already 7 year old technology. The Mini 5 has the same 500 nits. I use it all the time, and I've never felt like it wasn't bright enough. For both, the amount of space they use is mostly dependent on how much you download. If you have low, high, VFR, and approach charts plus high-resolution terrain for the entire country, it's gonna suck up a lot. If you have VFR and no terrain for a limited area, pretty small. The ForeFlight app itself is somewhat larger than Garmin Pilot, but only by megabytes, not gigabytes, and both are in the neighborhood of 1/4 gig. In ForeFlight, I have 41GB of documents and data downloaded - Jeppesen and government Low, High, VFR, Approach/taxi charts for most of the country, POHs and avionics/accessory manuals for both my plane and the work planes, several thousand pages worth of FAA-required "paper"work for part 135, and plenty of FAA and Jeppesen publications... And of course, when there's a new chart cycle, I'll have doubles of all the charts. Needless to say, I don't use a 64GB iPad.