My current grievance with DE is that I booked a J seat SEA-LAX-FRA in late-October. I thought the connecting flight on AS SEA-LAX would be in F. Nope. When you book a connecting AS flight through DE, they book you into the Q fare class. The DE website gave me only two flight options SEA-LAX. Looking at the AS website for both flights, same thing. But AS have earlier flights that day that do book into a first class seat. But here's the kicker. If I had booked the same flight through AS, my business class seat would be an AS D fare class ticket. Booking my flight through AS would earn only 1.5x EQM and RDM, while booking through DE will earn me 2x EQM and 3xd RDM. So unless you need to burn some wallet funds, booking through DE might be a better option.