I was just wondering whether anyone who is Oneworld Sapphire (but not through topbonus) can speak from recent experience. I emailed their service team to ask whether Sapphires can check one bag and pick a seat for free even in Economy Light and it took them less than a week to come up with this lengthy reply:
vielen Dank für Ihre E-Mail.
Auf unseren Flügen kann nur unsere Topbonus Card genutzt werden.
Für die Ihnen eventuell entstandenen Unannehmlichkeiten bitten wir um Entschuldigung.
Für weitere Fragen oder Wünsche steht Ihnen unser Team jederzeit gern zur Verfügung.
The gist being that only their topbonus card can be used on airberlin flights and they're sorry for the inconvenience. I'd have accepted this answer if it hadn't been so oddly unspecific – the way it's written ("only our topbonus card can be used on our flights") reads like they didn't even understand my question, because of course you can use the other Oneworld benefits on their flights, I just wanted to know whether that applied to baggage and seat selection as well.
That's why I'd like to ask any non-topbonus Sapphires whether they've had success checking a free bag and picking a seat in Economy Light recently.