This is a real problem for me, as I've got small hands. The Xperia Z Compact phones are the smallest flagship-level phone I've found. I loved my Z3C, sorta-like my Z5C. They're still a little too big, especially with a case on them, but they're at least not monstrously so.

> On the plus side, you can always stick a bulky battery case onto a thin phone.

That depends on a third party bothering to make a case for the device at all.

And it's way bigger and less efficient than having a bigger battery built in.