I love chocolate in soap too. Found out by accident, just tried it because I happen to have a stockpile of about 15 Kg callenbaut chocolate. I have dark and milk, only have used the dark so far. Lately I have also been using it to make chocolate candies, since soap uses it so slowly.
I wonder what made your first batch go bad? do you think it was scorching of the sugar in the chocolate? I guess 52% would have less cocoa butter and more sugar?
If you do not mind telling, how do you incorporate the chocolate into the soap?
This is how I do it. After light trace I add 30g chocolate with 30g coconut oil which I melted in the microwave. This is my superfat on about a Kg batch. I take a bit of soap batter aside and mix the molten chocolate and molten coconut oil very well in, then incorporate into the rest. When I use chocolate it is the only time that I soap at around 110F or 45C, hotter than usual (usually I soap from 95 to 100F). This is because I get stearic streaks if I soap too cool.
With the extra sugar and cocoa butter no wonder they lather nicely and feel so rich to the skin.