one more thing to think about
2 years ago when I got my s4, I learned that it was wireless charging ready. This meant I could bit an overpriced battery cover from samung and an over priced charging pad... Instead, I shopped around found the electronics to be inserted under the existing back, and 2 inexpensive Qi charging pads. This ran me over $100 and I thought it very worthwile. Last week I picked up my s6, with built in wireless charging. Went back online and found charging pads starting at around $5 if you are willing to wait for Hong Kong shipping, $7 if you want it a little quicker from a domestic seller. I bought 3 more, at a fraction of what I originally spent to get started. With 5 of these around the home and office topping off through the day is painless. (I'm even thinking about the console of the car.) As wireless power become ubiquitous, which I think it will despite apple ignoring this trend, I see less dependence on giant or removable batteries.