if u need a beige tote to supplement your black tote, go for the beige GST.
U have gold and silver Just Mademoiselle, in terms of size n capacity n functional use, the jumbo is closest to them... if u need another similar capacity and functional use bag like the Just Mademoiselle n wants a black to add to the gold n silver, then go for black jumbo.
The black and beige ml cf will add diversity to your collection in terms of size and functional use, i.e. when you need a smaller size bag for day wear and something more dressy than Just Mademoiselle, the ml will come into play. when u need a small bag for evening but want something that has a strap and or warrants a dressy bag but not as formal as a clutch, the ml will come into play too. When you need a nice bag that transitions well from day to night, the ml is best. Either black or beige looks good. if u want both black n beige eventually, then go for beige first since they r discontinuing it. on the otherhand, perhaps Chanel will come out with another oov beige shade that u may like better?