You aren’t gonna get much aero benefit on a gravel bike, so leave the rim height off to the side…it is largely immaterial.
So your question comes down to added benefit of 3mm internal rim width (wider measured tire, less PSI, more comfort) vs. a pound of wheel weight.
I know we are discovering more and more that weight doesn’t really impact results, but I keep looking at those +440g in my old-school roadie eyes like 
I think I would lean towards the carbon wheels, but I am also not saying that is the definitive answer. I guess I would set them up with the same tires and then ride them back to back days on the same hilly-ish loop and see how they feel.