As for the outward route, Deutsche Bahn seems to be in a right state. Every train late*, and don't trust them to recommend your route or honour your seat reservations. (*Crucially our Berlin change. Arrived 30 mins late, contemplating emergency hotel... but ongoing train mercifully also late)

But anyway, the ES is a great project. Still very new, but already bringing in a new route (Brussels-Munich-Venice) early next year, and introducing a diner car this autumn. Well worth supporting. www.europeansleeper.eu