Restore it as new, and none of those issues will arise.I don't dispute the usability of improvements. I partly regret not having iOS 10, I could have some use for Safari split-screen, which isn't available on iOS 9, it was introduced on iOS 10. The iPad experience was surely improved in iOS 11, but I have no Apple Store where I live.
If anything goes awry, Apple won't help. I cannot have the device I use the most crippled by an update. It's too big of a risk. I cannot have performance dropping, crashes, and battery life decreasing. Because if any issues arise - and I am not saying they will inevitably arise - I cannot fix them. Neither can Apple from here. I'm out of luck, and as long as it works fine, I'd rather stay without the improvements but have a perfectly stable iPad.
I have never had a crash on my iPad Air 2 since I bought it. Sounds like people are running some sketchy apps.