If its anything to go by...
Z1 vs Z5P battery
Z1 lasted the day on my avg use.
The Z5P seems to get down to about 45-50% in a day, starting from 0500-approx 2300/2330 in a day.
And for my test I did not activate any battery saver, yet. And I used Skype video call, on mobile data while out, for nearly 2 hours(various calls). That was approx 100meg data. Phone did get a bit warm, but otherwise ok. Vid quality on high, had to test while I still have the 100GB to play with.
will try that next week- battery savers