I wouldn't bother booking this "Euro Business" on its own but as, like your flight, this was part of a longer trip and I got it as a "sale fare" it was ok.
Our flight to Sin left about midnight and we got back into the non-Schengen lounge at about 21:00 and there was plenty of room. I think there were only a couple of long haul flights to Sin and HK around midnight - still bright outside. I didn't have a sauna but did have a very nice shower. It is a very comfortable lounge for lazing - if not eating.
I am looking forward to your posts on the Berlin part of your trip.