Last Friday I arrived at the 200 gates from LHR (lengthy immigration queue took approx. 30 mins) and also departed Saturday for LHR from the 200 gates.
I had a B2B yesterday LHR –DUB - LHR and again the 200 Gates were used, which was ideal.
Maybe those assigning gates at Dublin read this forum and are taking pity on those doing B2B at Dublin