I have Splices and I use Fire and Pink Iridiums as my two lenses. The pink lenses do work well in overcast conditions but they are not as effective when the visibility gets really bad (used them one in around 30ft of visibility and didn't have much contrast at all - hit a couple of bumps I couldn't see). For conditions like those Hi-Yellow would be better but Pink Iridium does just about work.
If the conditions are generally just overcast then Pink Iridium will work fine and will carry you over if the sun comes out (Hi-Yellow will not be great in sunlight at all). So at the end of the day it depends on the light conditions, if they are really low/flat light then Hi-Yellow if they are low then Pink Iridium would work.
Just found this which should help.