Thanks for the advice everyone. Makes sense.

Kirk - quite true about the stain colours. In my case it's Pyrogallol (PMK and WD2D/H). Even then, the stain colours produced by these two Pyro-Metol developers are not the same. PMK tends more to green-yellow while Wimberley's formula is more yellow-orange. Apparently the different alkalis have an impact on stain colour as well.