How often are you running you Macbook in a non-charger-available environment where you'd run your battery down enough to test this? Or have you specifically disconnected to test this? (Not /s, actual questions)
I am working outside (parks, beaches etc) while my little son and my wife play or relax next to me, so it's pretty much every day, with a new macbook I started to get stable 6-7 hours while using sublime text, but with Atom I am only getting around 4 max, so the difference is pretty dramatic for me.
I have done some tests, not on a 15 but a fully specced retina 13 (mid 2014 model).
If I am running a couple of iTerm windows, chrome for the dev tools (even though this eats up more battery then safari) with a couple of tabs open and sublime tex i'll get about 6 hours on average running my normal workflow. If I switch to Atom instead of Sublime I get just about 5 hours.
This is down to ~10% before anxiety kicks in and I have to return to the cord.
Worst case no cord, it just sleeps, right? No reason to worry, power is always close at hand, and hopefully (!) none of your files are just going to vanish if it does so.
When I was in school, most of our rooms had power (or weren't more than 3 hours long), but I definitely understand the sound complaint. Get a full classrooms of laptops under any strain and it gets deafening quickly.
