Thank you, a good perspective. I had a Lumia 520 three years ago, which btw was absolutely wonderful on WP 8.1! Post that I opted for the Note 3 (for the S Pen), and then got invested in the Android ecosystem. Now I have a Nexus 6P, which by all means is a superb Android device, and my Note has gone to my wife (she is very happy with all the shopping and to-do lists she can write on the screen :smile
I think I am judging Windows 10 Mobile based on the fact how crappy it was on the Lumia 520. Gosh those fabled resuming screens and super-lag! Then apps wouldn't update sometimes, and when they did some would break etc. I kept reverting back to WP8.1, and was astonished at the night and day difference. I tried using it as my daily driver on W10M, but would get frustrated by the end of the day. Since I could not do complete justice to the insider program, I shut my Lumia, and went back to my Android.
That experience taught me I don't have the patience to test out unreleased software. It also taught me that curiosity does kill the cat sometimes. I have not had the chance to restart my Lumia and install any latest builds yet (the last I installed was 10586.36) so I don't know what to expect currently.
So here is where my gripe lies - I am unwilling to jump ecosystems and put money down for a new phone, if I have to again enroll into the Insider Program (and I know I will want to, coz I'm the sucker that can't keep his hands to himself :amaze

. People that say the issues have been ironed out, how feature packed and stable are the RTM builds compared to, in my case, a Nexus 6P on stock Android? Is it a good buy in its current state?