The whole idea behind ending with quiet music is that it’s shocking because it’s different. I’m of the mind that the end music for the last entry in series should blow you away in some way or just generally itself apart, but I realize that sentiment is not universal.
I’m glad you enjoyed the experiment! It’s probably better with the ghosts anyway.
I could definitely get behind that idea, I think it would depend on the tone of the rest of the edit as to whether it would work.