I'm also looking at using Sherwin-Williams epoxy. This is an industrial floor finish. The tech guy told me not to mix the silica in with the epoxy but to have someone wearing something like a pair of old golf shoes follow after the sprayer has completed an area, making sure you to this soon after the application of the epoxy. Then toss the silica into the air over the wet epoxy. The formulation of the epoxy is such that it will "fill in" the holes left by the spikes on the golf shoes. He said that in their experince with the epoxy they found if you mixed the silica and then rolled the epoxy on it would leave streaks and ridges. At that time I was looking for info on floor finishes, but now I am close to the point where I need to nail things down. Within the next month to month and a half I expect to be at the point where I will need to do the floor. He also said that they do not recommend putting their product down until at least 28 days after pouring the concrete. I'm sure you will be done before I start but I'll let you know what the final decisions are and how it turns out.
Leo