I've been seeing excellent battery consumption during sleep mode.
I don't use (and have in fact uninstalled) touchwiz and much of the Knox stuff.
I've disabled a lot of services using the excellent Disable Services app in the Play store, and I've also set Greenify to be very aggressive, including using the Xposed module to enable the paid version to sleep system apps.
(As an example of stuff I axed - all of the S-note and S-pen related stuff, all of the Samsung sync functionality, Samsung's silly calendar replacement.)
The Snapdragon 800 has some very good sleep and battery conservation available to it, if you don't let Samsung and Google keep it up all night.
There's a lot of great info in this thread: