I think white would be a better choice, but you can leave the island gray.

how about a silvery gray for the cabinets with nice brushed nickel hardware and paint the island a charcoal gray or black.

Yes, too much gray. It looks dark, is it?

I love the idea of painting them. I would take the color of gray from your island, step down one to two shades lighter and use that. That way it will look great together, but won't be an overwhelming amount of the same color. Good luck with your project!