For some time, I see problems with the power button: it activates without contact, and my N5 reboots without even having time to finish each startup! I removed the shell, and the problem has disappeared. From what I could find elsewhere (including in a conso opinion on the site Spigen), the hull too enserrerait the phone and cause a contact on this button.
So I will definitely point me to a flexible silicone shell, albeit less elegant, but also less stifling for the phone.