I don’t think free placement is a seriously stronger handicap than default placement. Default placement is good. DDK would easily get over-concentrated if you allowed them free placement.
I was the referee in a tournament with handicap games. It was EGF rules, so free placement. But actually, most players don’t even know it’s free and put them as usual.
However, one player came and ask me about it. After I told him he was free to place them however he wished, his opponent was pretty mad about it and tried to convince me to forbid it, even calling it “disrespectful of the game”. (So here you go about etiquette, some people really don’t like free placement).
It was a 9 stones games. Black made something like 4 shimari + tengen (I don’t remember exactly, but that was the general idea of his formation). White won. I think 4 shimari is decent, but not better than 8 hoshi.