If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
It sounds very appealing to me, but as KaynanK pointed out, you have to be very careful about keeping the twist secret. To this end, I'd suggest not revealing to the players that they could have gone off-script, unless they do.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.