Thanks everyone. I ended up with Qantas First and chose not to move to AA Flagship, simply as I was settled. I didn’t find the table service slow, very attentive actually.
I was also partly influenced by doing a ‘lounge-run’ in the outbound of CCR, First, then Galleries B gates.

on a separate note, I wonder if LHR will create a C-Gate lounge as part of a solution to the logistical and capacity challenges the upcoming Lounge refresh/ refits will bring in A Gates