how about an iP6? battery wear is about half way down and was forced to use a mophie case (i drain the charge in the case every day). the iPhone 7s/8/x/edition/pro can't come soon enough.
I want the new iPhone that's coming out this Fall and I'm due for my upgrade then, so that's my plan. Maybe I'll bring this in after I get my new one and get the battery replaced and keep it as a backup.
My 6S is eligible for a battery swap but haven't had any issues. I'm on 225 cycles or so. Wear varies between 6 to 12%, so I'd say it's holding up decently for a phone that soon 2 years old.