On point to point LHR to DUB BA is consistently more expensive than EI. With the hand baggage only fares the only difference between the two is a pack of chips and a drink on BA. After EI moves to T2 at Heathrow the overall airport experience will be better with EI. BA is still using grotty old T1 at DUB which despite the makeover is still pretty tired.

I would imagine DUB is mainly a.long haul feeder for BA rather than a significant point destination.