I'm down for getting black/black in addition to gray but I don't want one order to cannibalize the other. Seems like there is demand there so far but maybe not enough to get 24.
In terms of design, they only offer one gray which is a heather flannel:
Here are the straps, I prefer the darker brown but would be fine with the lighter. I think the tan color posted earlier is a one-off.
For the undervisor the default is satin green, as alternatives I'm fine with either of these three (would have to confirm they are available):