Software apps can have a big impact, the differing services, and even carrier software, for example.
Some background processing "weirdness" is happening on >=AU builds, or at least I'm seeing significant battery and app usage, when the app was never used, yet it shows "foreground" drain during a time period (6 or 24 hours).
Firmware can be specific to carriers too, although it shouldn't be, in the case of the 950XL, in the US anyway.
I had that extreme battery-drain issue, and then a secondary less serious one, where I ended up doing 3 hard-resets, since the AU, that's at least 2 too many, or really 3, IMO. I did 1 hard-reset in all the Threshold builds (Release Preview) prior, in about 7 months, and that wasn't really necessary, like these others.
My Bluetooth doesn't work consistently since the AU builds too, maybe it will work, sometimes, or not, or maybe after 1-2 reboots.
It's a bit troubling, reliability just seems to me like it's at an all-time low, but I wasn't running RS builds before either.
Things are definitely unstable right now, maybe the "real" release will stabilize them, I'm hoping so anyway. As far as I can tell, there's still not been a final general release, unless I've missed something?