Developer preview. I dont get why people just dont enroll in it, it's stable and especially things like the web browser have become dramatically faster.
If your worried about stability, my Iphone 6 with IOS 8.1 has more bugs than any of my devices on DP. So if you really want to get the most out of your device just enroll!! If/when the official update comes out you will still get that update too, as I have witnessed on my 1520. So would advice anyone with Ativ or any wp actually just to do it. My phone is on standard firmware I have a international Atvc S model and have enrolled it in preview for developers.
Btw is Changing you CSC the equivalent of Flashing a rom/downgrading? Cause i've had to do none of that. And with this new update I would advice against it. Microsoft has promised and has now delivered.