I don't agree with the action open biz on a semi auto handgun. I'll check it before I hand it off. I'll check it after I receive it. But I think a semi auto with the action open is one step closer to a loaded gun. If the other guy doesn't believe it's empty, then good. He needs to check for himself, anyway. And it needs to be treated as if it's loaded, either way. Saying you must hand over a gun with the action open is like saying you need to put the safety on.
The "I'm the only person professional enough to handle this Glock 40," video comes to mind. He demonstrates the unloaded gun with the slide open. Drops slide release. Shoots foot. I know the first thing someone will do when they receive a locked open gun is to drop the slide. I want to be the one closing the slide - slow enough to see and feel it's empty. I prefer to not give someone the chance to pick it up and drop the slide release, anyway. Aside from stressing the gun, dropping the slide with a release is just not a good last action to verify a gun is empty. It puts a question mark back into the equation because it happens so fast and it's the same action used to load a gun.
So for me, my guns are never safe. But the safest they get is when they're emptied, slide closed, and chamber checked, then treated like they're loaded. The other guy can repeat it all over again, for himself, however he prefers.