I have recently been involved in maintenance on a Lancair Columbia. It addresses the problem in two ways. Firstly they have installed a simple door jetison system accessed from the belly panel which is a simple cable that when pulled by rescue crew releases the door hinge pins. A fairly simple mod to incorporate in the build stage of any gull wing door type.
And secondly they supply the pilot with a fairly substantial Axe!
Somehow though I feel that with most aircraft that turn over most of the transparancies will be cracked / broken no matter how gently the flip over is.