Well mixing the selectol soft (metol only developing agent, lower carbonate alkali rate as well I think) with the dektol cut the ratio of hydroquinone to metol, since dektol has both HQ and metol. The HQ is super additive to the metol ie both develop faster together than either one on its own.
Fo a real treat, develop two bath in dilute selectol soft first , say 1:1 2' at 20C, then second bath of dektol 1:3, at perhaps 10 to 20 seconds depending on how much you want of the blacks. Do in the other sequence and you need a good rinse or you carry the HQ in the dektol into the sotectol and the soft goes away quickly.