iPhone 6 Plus Bend Test
See how with a lot of pressure the iphone 6 will bend this could possible happen if you keep in back pocket when sitting down,
Only time will tell if this happens with normal use, Thinner larger phones more likely to happen.
I myself would not leave any phone in back pocket when sitting down likely to crack the screen specially on larger phones.

Galaxy Note 3 Bend Test (iPhone 6 Plus Follow-up)
Here is same test with Galaxy Note 3 you see the bending has very little after affect.



Consumer Reports Bend Test Pits iPhone 6 Plus Against the Competition
Galaxy Note 3 came out on top, withstanding an entire 150 pounds of force before giving out,
while the iPhone 6 Plus took only 90 pounds. The LG G3 had a strong showing at 130 pounds,
and the HTC One M8 and iPhone 6 came in last by withstanding just 70 pounds of pressure.