Finally GM is paying out as they promised yesterday:
So I guess they have solved (most of) their problems (server upgrade after hack). One problem remains: I have still a lot of ETH in my balance which they did not payout the last weeks. Will get in touch with the costumer service.
My future plan with GM: I will wait two or three days and see if they still pay out, then I will do my upgrades. And we can play our beloved Code-game again: If you use my code ("uVQCWJ") - I will use yours (but in the comment section)!