Completely agree, same for me. And yes, exactly, the flight that always arrived at a bus gate for me was the mid morning from LHR arriving around 16.00 that you mention.

Of course, as always, it depends on how risk averse one is and one what stands to lose. The risk of things going wrong is well above my personal threshold here, and if the "cost" of missing the B2B would be to potentially risk losing a long haul ex-HEL, I personally wouldn't touch a HEL B2B with a barge pole, sorry.