Liberty and 6 oz of Cobra together is fine but I have no experience adding the S Metalachor with it.

Even 6 oz of Cobra will bronze the beans really good on a hot humid day.     You will easily be able to see any skips the day after you spray and the beans will look pretty rough until new leaves come out.


Also, 6 oz of Cobra is the rate for white mold, that rate won't do much at all for weed control.    I believe 12 oz/acre is the rate if you want to kill weeds and then you should probably go fishing for a week after you spray the beans.   They might be starting to green up when you come home.