Generally the suggestion is to vary the island cabinets or counters, but not both. Not to say it can't look good mixing both up, but it's more risky of looking disjointed particularly in smaller spaces. Instead of painting the island a light grey, have you considered staining it?
This is my kitchen, I think the stain really gives a nice contrast, interest and warmth to the space. It is also more durable than paint (and cheaper). I used a very light grey paint, would have worked with white too though.
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Colonial cream
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