Aaron from Sage Dynamics torture tested all of the current red dot sights on the market. The DPP and other ones with a larger window shattered when dropped from 6ft on concrete:
http://docs.wixstatic.com/ugd/7dc128_50a7c57f2d284e53bca8584a7f7925b1.pdf
The consensus was basically, if you're life depends on it, and you're using it in a "duty" capacity there's a reason why the RMR is used by military and police forces. Anything short of that, and one of the other smaller windowed dots will probably work fine, include for HD or SD carry.
The Holosun 507 did very well for it's $250ish price point.