Moissy performs less preferably in overcast environments. There is some warmth, and their is (in some stones) a little tint of green now and then. I think in the sizes you are looking at, however, moissanite is a fine option because the funky color doesn't start happening until you get to about 1 carat stones.
If it really concerns you, you could splurge for the amora color enhanced stones. But if I were you I wouldn't because your stones should be pretty white as is.
Of course if it really concerns you, you could wait for asha, but I don't think you need to and I'm pretty sure you would be happier with moissanite in the long run because it will never cloud. I always have problems with my earring, of all things, clouding..
Dream in Pastel!