During my Vulcan time I do not recall any occasions when I rolled from an asymmetric approach. A simulated Double Engine Failure After Take off was initiated by throttling back the pair on one side. After a routine heavyweight circuit and instrument approach i believe 93% on the working pair was more than enough for a safe climb away. Asymmetric safety speed was one of those things demonstrated on an early OCU sortie, never approached again in real life.
OCU QFIs may well correct me, but I never found the excess power available a problem. Was roller from asymmetric landing demoed on the OCU? Too long ago for my memory.