Sorry for the necro 
I recently had to start using my 10iii for mobile network reasons (LTE), but before putting it to use I checked its idle consumption. Test procedure: Charge device, reboot, leave it idle with all radios and GPS off, occasionally check battery level.
Let me present the two contestants in this challenge:
- In blue: Xperia X 10 iii, unused with a handful of charge cycles, flashed with 5.0.0.68
- In red: Xperia X, bought second-hand and used as daily driver for 6 years, originally on 2.0.x and upgraded to every release until 4.6.0.15
The 10iii is holding up pretty well, but I realized the comparison was unfair. So I decided to plot the actual remaining charge in the battery instead of percent charge:
I think this shows the 10iii’s powerful, octacore idle better, half the endurance (5 days) on a battery that is twice the capacity.