NoD/Triplebravo,
Please forgive/correct me if I am wrong but I thought that the certification basis for all types takes no account of the contribution of reverse thrust in the calculation of landing roll distance required. "Best performance" will certainly be achieved with full reverse, especially in the wet, but its main function is to reduce brake and tyre maintenance costs. If this is correct then the selection of reverse before spoilers confirmed out puts DOCs above safety.