There were rumours that a 75 could do ACE as it won't be runway limited. Full loads off the northerly runway with the wrong winds often result in a tech stop getting back to Dublin for the 320/1. Will have to wait and see what pans out.
Even a tech stop can work out cheaper than running a 757 on a route; the
Renton Rocket burns a good 1.5 tonnes more per hour than an A320 in cruise.
It can haul an extra 50 pax in high-density config but that can't outweigh 50% more fuel ( and that's a conservative figure ).
Overpowered == inefficient, sadly.