If I was you I wouldn't wait a single moment more, all I've heard from you since you began posting are not normal behavior, you should get a replacement and go from there.
Again, this phone will never get less battery life than the Moto X 2014, that one had a Snapdragon 801, 5.2" screen, 2300 mAh battery and the regular last year specs all around, Galaxy S6/Edge has a better and a lot more optimized Exynos Chip, Power saving Memory, power optimized 5.1" Amoled Screen (Even when it's Quad HD), power Saving memory and so on. With that in mind and seeing that most of you are complaining about the Standby battery drain, it's obvious that the only one spec that can affect the S6/Edge battery life (Quad HD screen) is not the culprit, then it's 100% software related.
So, only thing to do here is wait for T-Mobile to fix it (Some people must complain about it if not they won't even know about it) or be pro active and begin doing what it has been suggested here and in other forums and try to pinpoint the issue. Like I've said dozens of times already, turn off the Smart network settings on Wifi(If you have it on the S6, I don't have mine yet so I don't know) and the Scanning Always Available option in Wifi advance Settings, you won't need any of that.
Wifi calling, same as GPS (Location) and Bluetooth, you can turn it on when you will use them, no need to have wifi calling always running if you know you won't need it.
I'd love to have mine so I could be doing all this things myself and posting my screenshots of the Battery Stats, but not until next friday at least, so for now I (we) depend on you early birds on do this stuff for us and see what happens.