I've flown DE three times between ANC-FRA (RT in 2012), (OW in 2016) and (OW in 2019). I enjoy their hard product (have only flown in Comfort/Business), and the route is second to none when it comes to getting to Europe from ANC. However, their customer service is atrocious in my experience. I've even been yelled at by the phone agents for mistakes that DE made. I'd say there's a snowball's chance in hell that your miles will get posted without numerous additional attempts on your part. Prior to the partnership I had to mail my physical boarding passes to Germany to get credited for my Miles & More account (no exaggeration).