In your experience would there be much difference in rolling resistance between this mild hybrid tread that I have (Kenda Kourier 700x40, at 60psi):
And this slick-with-rain-channels tread (Kenda Kwest 700x38, at 60psi):
Just the tread pattern issue in isolation. The tires are otherwise similar in width and weight/puncture protection. I'm not talking here about switching from mountain bike tires to skinny high-pressure racing slicks.