Originally Posted by
corporate-wage-slave
A lot easier: there is a connection channel in T2, which there isn't in T1. So FR to BA will now involve a lot of walking and a busier security zone, BA to FR a lot of walking (and you're not supposed to use that channel but no-one will stop you), B2B won't quite as easy as AMS or CPH, but easier than BCN.
For the lounge question, there is another airport-wide lounge in T2 quite similar to the existing facility in T1, but there is also Aer Lingus' own lounge, which I suspect will be used now, and is somewhat better than the airport lounges.
B2B is likely to become a lot riskier.
During the middle of the day, most of pier 4 is turned over to TATL using preclearance on the lower level. EI usually keep one or two gates close to the terminal for their LHR shuttles. Everything else short haul goes from pier 3 or the south gates. Pier 3 is a long walk and south gates are bussed. Im not sure if the South gates are segregated but they are relatively new so I expect they are. This would require a bus back to the main arrivals stream part way down pier 4, then looping back through transfers to get the bus again!