To me, sometimes updates can come with additional issues. On 8.1, I don't recall ever having to hard reset or be concerned about random restarts (for some reason, I have only had this issue with the 950, no other native W10M phone). The difference in stability between the two is something that cannot be denied. I kind of see it the same with iOS 10. iOS 9 has been just fine to me, so I downgraded my iPhone back there.
You see, this right here is the thing. With iOS, 9 times out of 10, if you get an issue, you can resolve it via the menus or via a simple turn off and turn back on. With W10M, my issues couldn't be resolved that easily. And bug reporting via Microsoft is good but even then they don't listen. The number of people asking for specific features that had long since been ignored. Microsoft really dug their own grave with this one.
I was hard resetting the phone every week! I even had one day where I had to hard reset the phone twice in a single day. I mean, come on, I know there are some W10M fanboys in this thread but no-one can sit on their high-horse and say W10M is a competitive, fantastic OS when the advice that comes back from the net is: "hard reset it", "soft reset it", "re-install W10M".
And this is precisely why I got rid of my 950. Bug hunting / searching for fixes became a full time job. Seriously. For every issue I solved, I found another problem. And when I installed the Anniversary update, I encountered a few more problems. Using Edge for example, the only browser on W10M (excluding the crappy alternative in the store which is said to be malware in disguise!) would consume so much battery life.... I had to sit next to my desktop computer, search for guides on how to fix it... ugh. No. It's just simply not practical.
I can personally say that I didn't get random reboots like some people have. One guy on this forum said he gets at least 1 reboot per day. If that was me, the phone would have been sent back within the first few days. The mobile phone market is so difficult to break into now and we're seeing Apple and Samsung at the top - other manufacturers don't get a look in. To beat Apple and Samsung, you need something not just as good, but much better.
Anyway. I don't really check this forum now for obvious reasons but I will absolutely keep an eye on W10M and see if anything changes. If it does, i'd consider returning. But there would need to be colossal changes for me to even consider it. Outlook's app on iOS is damn near perfection and a joy to use. If W10M had the same app (look, feel, fluidity, reliability etc) W10M would be a better experience for that alone.