That doesn't seem so much different from a transcon flight in the US, which is mostly no big deal.

Even though a narrow body isn't as conformable, I'd much rather fly direct as generally the alternative is two flights - a narrow body to a hub and then a heavy across the pond.

Long-haul on a narrow body is fine as long as the seats are good. QR used to do an all-J A320 LHR-DOH which was a great way to travel.