As for me, if ever I expect to do a crash landing, or an emergency landing where departure from the runway is more than remotely possible, I will certainly unlatch the cockpit door. Fully opening it is not advisable, as tat door can provide lots of protection from unsecured objects in the cabin, but cracking the door is a good way to minimize the risk of the door becoming jammed due to frame bending. The window and hatch exits should remain closed, as again they offer lots of initial protection, and add to the rigidity of the airframe. The cockpit door, however, serves no such purpose. Crack the door!