It is just as durable as a Glock frame. Part of the strength of these polymer frames come from having the mag inserted, and the metal slide on top.
As long as U don't jump up and down on it w/i the slide on it and a mag inserted, U will be fine.
Even all of those stress tests of the Glocks - where they drive a truck over the gun, has the mag inserted.
I wouldn't worry about the polymer framed guns. In fact - they probably lass longer than some metal framed guns. They seem to handle the stress better by flexing a bit during the firing