Elephone have sent over a video that shows (in a non-scientific) the differences in strength between the P8000 chassis and the iPhone 6 chassis.
Whilst we cannot be certain of the exact amounts of pressure being exerted upon the different frames, it does appear that the P8000 has a distinct advantage over the iPhone 6 (and most likely over the P7000 that came before).
With the release date set for the 25th of July we should hopefully find out more very soon.