We have received very good value from our FlexPerks points so far (two last minute tickets with a cash value of $396 each for only 20K points each). We directed a lot of spending to the DL Amex after signing up in June but switched it all to FlexPerks in Dec. We will cancel our DL Amex before the renewal fee appears. The ease of booking a FlexPerks award, the choice of carriers, the ability to earn FF miles and get upgrades on the flights, and the $25 reimbursement for expenses during the trip are all icing on the cake. Worst case, each Flexperk point is worth 1 cent in statement credit.

If you're targeting overseas travel, the picture can be a little less clear. A coach ticket from DTW to FRA purchased now for summer travel will run you 70,000 FlexPerks points (as the cash fare is probably over $1,400). But you could (in theory) get a DL award for 60,000 miles. Business class awards may also skew in favor of DL miles but, again, it depends finding "Low" DL award tickets. There is never a problem with "availability" of FlexPerks awards.

In your specific case, you really don't have enough FlexPerks points today to go to Germany. You have plenty of DL miles, even for a "Medium" coach award and that should be easy to find. Add another 5K miles and you might get lucky finding a 100K business class award. That would be nice. But going forward, you probably want to opt toward accumulating FlexPerks and don't bother with the Amex.