Davis is so much faster in all aspects than Rashad that it's going to be laughable come fight time. He can shoot for a clinch throw, change to a double, switch to a single faster than Rashad can tweak his nipples.
The size difference will be pretty considerable as well.
Davis is fast. Very fast. But I don't think the speed difference will be as significant as you suggest. Rashad is as fast a LHW as they come. In terms of shooting for TD's, Davis may be SLIGHTLY better. But I bet in the striking exchanges it will be the other way round. Rashad's comfortable striking and very loose whereas sometimes it seems Davis is tensing up and he has yet to be 100% comfortable with throwing strikes the way he can shoot. I guess that will come with experience, but don't be surprised to see Rashad beat Davis to the punch on most striking exchanges.