I've been wanting to run an urban campaign for a while, and the thing that resurfaced that idea in my brain is the 5b death and dying rules. It is easy for both player characters and NPCs or monsters to knock a character unconscious instead of outright killing them. That made me think of tavern brawls, arena fights, encounters with the city guard, harsh laws for murderers, etc, and how these rules accommodate such gameplay.......
I have a big issue with that rule, which comes from 4E, where I had a big issue with it.
First, for you and what you describe, it may work great. Essentially you are shifting in the genre a little, and what you describe sounds great.
As in a supers game and probably some others, it creates that situation where damage is usually non-lethal, and someone will make a choice to "take someone out"... permanently, which is an interesting choice.
But thats also the problem. In the more standard FRPG genre, you don't want that choice most of the time. Its easier not to have it. You may want the option...but then that should come with some penalty or require using certain weapons or tactics (like the bag of gold).
What am I talking about? The characters have lethal weapons (swords...fireballs) that they need to defend themselves as they selflessly salvage lost items (which they selflessly keep) or they need these to stand up to some evil. They don't want to kill a bunch of things, but thats just what happens in this dangerous world. The don't have a choice.
Think about how lethal force is justified in real life. If you change reality, so that swords are just as effective in doing non-lethal damage, but you kill anyways, what does that imply about the killers? Robust adventure (or military action, or police action) becomes much more genocidal.
I think that rule work because people ignore it. If you think about it, its a problem for games that are not 1) like a supers game (A team style!) where lethal force is rare or the other extreme 2) where everything that dies should because it deserves to (which probably would include the PCs at some point, I guess completing the circle). If the game is in between, that rule creates a bad choice, over and over again.