I'm simply amazed that the US won't be getting this for a while yet. I stopped using my Lumia 950 XL months ago and went to my Lumia 640 running the exact same Windows 10 build and it runs faster, less buggy, and has an honest to goodness, real working WiFi.
The Lumia 640 has an honest to goodness real working 2.4GHz Wi-Fi to be exact, which my Lumia 950 XL has. I don't think I've noticed many problems when I'm on 2.4GHz. It is only 5GHz that I see problems with the Lumia 950 XL.
As far as "buggy" is concerned, no. i don't see the Lumia 640 as less buggy when it is on the same build as the Lumia 950 XL. I keep a Lumia 640 on the production build so that I have a fall-back device should I have problem with he 950 XL which has always been on Fast Ring and has always been my daily driver.