I personally think you'll notice more of a difference going from grass to a rubberized track than you will from spikes.
The biggest thing about shoes, IMNSHO, is that they produce a placebo effect, making you think you are quicker, so you may actually put a little more effort into it than normal.
I was more of a distance runner, but I've actually seen times GO DOWN when people put on spikes because they were less comfortable and energy absorbant than running flats or training shoes and the person was in pain from them. But that's in distance running, not sprints.
I would think the track type, and an efficient start would yield a better time than the shoes worn.
Once again, just my opinion though based upon experience.