Mike:
If you carry a double rifle open in the field, the day will soon come when you will not be able to close it in a hurry, and on DG your life may be at risk! A single grass-seed or tiny twig on the flats will prevent a quality double from closing, and it takes several seconds to identify the problem, re-open the gun, determine which side of the lumps the obstruction is on, and clear it. You will invariably take your eyes off the quarry during this process.

I abhor the practice of carrying a double rifle open! It places the inherent reliability and quick-pointing of the double in jeopardy: might as well carry a bolt-gun!