If your going run harness at them speeds i would go with one made with a wire leader. Heavy mono and floro will work but will wear from the clevis & beads and will eventually break off. As long as you check your harness periodically for wear and replace when nessecary you will fine.
Willow blades will put less stress on the line then Colorado blades at higher speeds but still wear on the line.
Leadcore,dipsy,riggers, snap wieghts, all will work. Don't get hooked into all the hype of how it should be or how it has to be fished. Worm Harness is not reserved for just bottom bouncers and slooowww speeds it's more like fishermen reserve the harness for slooowww speeds and bottom bouncers. Fish them like any other trolling bait.
I'll run harness along side spoons & body baits at 2.5-2.8mph no problem,with a wire for the leader. 18lb 7strand wire with a high speed swivel.
As far as favorite colors go I don't real have just one. Just like other baits, many colors from one end of the color spectrum to the other..who knows which color the fish will favor on any given day so I find it best to pack a few differnt colors.
The Fish will always tell you what color & blade style is best on that day.
View attachment 63477View attachment 63478