I have just started using my new Merkel GDR drilling, 16/16/7x65r as my "go to gun" for big and small game. Without the scope is a decent carry gun. Yes, I've lighter, but not bad.
The real issue for things like grouse hunting is the Greener safety of most old drillings. I've gotten pretty good at getting if off while mounting and shooting the gun, but its slow and not easy... I did manage a nice woodcock back in January.
My original idea for a drilling was what you are thinking about a close quarters "whatever comes out" gun for the Eastern woods, back when I lived on the East Coast. A lighter drilling in 16 or 20, with a 7mm or 8mm rifle, no scope (or scope in quick release mounts and in my backpack), all ready to go. In areas where grouse, woodcock, turkeys and deer are all in season I'm convinced it is a sound concept. Though I left the East coast before I got mine... ooops...
