To be honest, if they pay out the EU compensation that you're absolutely due, that's probably as much as you'll get. Technically, they rebooked you in business class to your final destination, so there was no breach of contract. Yes, I know the business class in question was shabby, but you just wouldn't have much of a case except hoping that LH extend a token of good will. And after they've paid you 600 EUR, I don't suppose there will be much good will left