mlee 2500 :
The conclusions in this article may or may not be right, but they are extrapolated from entirely faulty logic. Namely, when, how long, and how often is that power draw applied.
Yeah. For all we know the Snapdragons have better (more granular, faster) power/clock adjustments. They also might be more efficient at the majority of the power curve, merely having a similar top-end draw. It also doesn't factor in performance. A higher-performance chip won't have to spool up as much and/or as long to complete the same task, so if draw is the same but performance is higher you can sleep more. Similarly, the number of cores and core configuration are big factors. If it's big.LITTLE there will be opportunities to shift low-demand workloads to the more efficient small cores. Speaking of which, workload is always a factor. Basically just looking at TDP ranges isn't enough to guess battery life.
Even the SD850 will be a pretty substantial upgrade over the 835 devices. With that being said, the biggest factor for ARM in terms of raw performance is how much software (be it UWP or Win32) can they get native compiles for.