Your story is pretty interesting, thanks a bunch. I have been using Opera for a long time, also, perhaps more than 6 years (since version 8, when they made it free) and I hanged to Opera 12 for a while until I found Opera 24 or something was as good as 12. I still use Opera Mail.
My story is very different: I have three laptops only, no smartphone, one of them a very light Windows 7 Home computer (I have no idea what processor it has, but it was dirt cheap), a very potent Windows 7, rather old laptop with an i7 and NVidia, and I received at work a couple of weeks ago a Windows 10 ASUS, also an i7 with Nvidia with a fresh OS installation.
In all those systems I have had no freeze or compatibility problems. The little laptop I mentioned is the one that surprises me more: with a very light RAM and a very poor processor, Opera shines over Firefox or Chrome, specially if you install in those browsers the equivalents of all the bells and whistles Opera has accustomed me to.
I checked some of the pages you mention (most I haven't heard about) and I found no problems, probably because I just browsed them quickly without delving into them. I'm curious and probably will check again in depth, because I still have to find a page with lack of compatibility since I moved up from Opera 12. I imagined that the lack of compatibility problems happened because now Opera has the same engine as Chrome, so your story is quite a surprise to me.
I conccur with you on one thing: I also think that the communication between users and developers is very limited and that's an issue that perhaps could be solved in other way, maybe by including some kind of reporting system that is readily visible and solves problems for people in your situation.
Frankly, Opera has always been a time saver for me instead of the pit of despair any software becomes when it takes your time away.
Opera has been, to me, a quick and rock solid way to browse the Internet. I wonder if I'm lucky or perhaps I don't use the browser so intensively as you, although I'm a developer for a GIS leader internation company. This means I routinely extract till the last drop of graphic capabilities the browser has.
However, I work as a Solutions Engineer, which means I have to diagnose the situation of potential buyers of the GIS we sell at our company. This had make me aware of, when you want to earn market share, how important is to take care of customers listening to them and reacting quickly to issues that become viral, like the ones mentioned in this thread (i.e. lack of compatibility in Win7/10 updates). This has to be dealt off quickly.
My experience about time wasted in Opera is very different: I'm used to other fellow workers watching occasionally how I use Opera and 5 out of 10 times the question is always the same: "how do you do that?".
I also wanted to comment that, although Opera is not that relevant in market share of PCs, that situation is not entirely true in smartphones, AFAIK, as it has half the users of Android Browser and way more than Firefox or IE (and the future is in that market, apparently).
So, I guess in life "everything is of the colour of the crystal you use to look at it", as Calderón de la Barca said.
I wonder what browser you will be using from now on. Could you tell us and, perhaps, in a few days comment about site compatibility? As they say, nobody (and no browser) is perfect.
Another question I have: have you experienced the same problems in Opera Mini as in Opera for PC?
Thanks in advance for any comments about Mini: I'm planning on buying a smartphone next week, after years of not needing one.