I need to book a one way VIE-LON itinerary, which will be flown within a separate TATL ticket issued by DL. The return portion of the TATL is the day after the VIE-LON segment.

U2 has a very nicely timed non-stop flight, with a Flexi fare that is about €50 cheaper than the next best option, KL.

KL timing is less great, primarily because of the AMS stopover, but KL flies into LCY (closer to my destination, and offsetting about an hour vs U2 into LGW). While as STE+ I'd get lounge access with KL, I'll happily trade that for a non-stop itinerary. (BA and OS non-stop timings aren't particularly good for me.)

The only thing preventing me from going with the U2 itinerary is the potential for IROPs. If something goes wrong with KL, they have significantly more options into LON, and worst case I can call up DL and they'll probably help me out. With U2, I think my options are much more limited.

So... what would the forum do?