Certainly, the cover is provided due to the size of the 6 + with a certain weight and a daily repeated opening and closing materialermüdend. Only that should not come to a premature destruction in the intended purpose.
For my 4S I notice a Piel Frama Case for over 3.5 years in use, when I can not get a break such material to date.
Too bad for the visually successful and pleasant to the touch Case