When the call is phone over just slide the offline switch down to hang up, it is very fast and an effective way to end a call. Good bye, click. No need to look at the screen, simple. Plus, they won’t be able to call me back if I leave it offline!
TIP: This might work best with Security / Screen Lock : None
(temporarily in v 1.6.0)
There is an option setting for the power switch press to end the call but I am concerned I could accidentally hang up using that method.