I guess a lot depends on the temperature of the cold water; is it below 70F or more mild like about 85F? When I wash darks, I use 85F water and a color guard detergent like Cheer for darks. I don't think there is much problem with grease being redeposited in the machine if regular washing is done with warm or hot water and sufficient quantities of a good detergent.
As for the speed, if you are talking about denim, that is probably OK, but most agitators are more violent at lower water level settings where the load can't migrate away from the agitator fins or, in some machines, can't even roll over very well due to the agitator/tub design so if you do not want any mechanical aging of your darks, you might consider the slow agitation setting or a higher water level unless your GE is one of the machines that fills almost half full at the lowest water level setting.
As for your choice of the cycle, I guess it mostly depends on the fabrics. Maytag's cold water cycle used a full tub of water on the normal cycle with normal speeds for agitate and spin.