I was asking myself the same question, though with Switzerland in mind. (Germany and Switzerland are the same area for EC with common conditions).

Earning status is far quicker and easier; miles and points are awarded on pretty much every fare - none of that 25% and 0% nonsense which ensures opprobium among UK members; miles earning and redeeming rates are different - check on this in the online handbook, as it may be relevant to your circumstances. You can earn BA Miles with a German Visa card. (The Swiss Diners Club card is better, with 2.4 miles awarded per £.)

The main handicap would be the loss of 1.5 miles per £ from the BA Amex Premium Plus card and miles with Tesco, but if they don't concern you, it could be a no brainer.