Went original iPad from its first year of release to the Mini, then Mini 2. Went Mini 2 to Air 2 this summer. All have seen heavier use than most people will ever do, because they've been 85-95% laptop replacements, all day, every day. While not quite as light as a Mini 2, the Air 2 is significantly lighter than the Air (which we also have in the house.) I carry mine in one hand all around the house, same as I did with the Mini. The only time I miss the smaller size is when I want to take it out and about. The Mini fit into almost every purse I own, the Air 2 only fits the larger ones. Solution...more purses! 😀
Would I go back to a Mini size tablet again? Probably not. The Mini just renders websites way too small for comfort. Video is better on the larger screen. And for any productive work (writing, light photo editing), the Air 2 is just better all around. For me, that outweighs the portability of the Mini by a lot.
(And yes, the Air 2 is a significant upgrade from any iPad...but I personally don't think it's worth the money upgrading from the Air if you already have that model. If I'd had an Air of my own, I'd have waited to upgrade until the Air 3...even if that's another year. We're not upgrading my husband's Air until at least that point; it's honestly still an excellent device.)