With FR excess baggage charges it really make their product to transit passengers un appealing as it usually matches EI in the end and their schedules don't facilitate a huge amount of transit.
Making a connecting after arriving in DUB at 05.15 is tight as FR main flights depart between 06.00-06.40 when you consider immigration, terminal transfer, check in (40 min before flight), T1 security and 10-15 walk to gate. Apart from some UK passengers I expect it is very small.
Now your not going to come back and say T/A don't bring checked baggage are u?