I note that apparently for 2009 the Kona Ute has some changes. It is now listed as coming with 700 x 47C tires and is listed as available in two sizes.
The original post in this thread indicated only one size as available and mentioned the relatively narrow tires as an issue.
For a cargo bike I would still prefer a steel frame. A fatigue crack on a aluminum frame with a full load would not be any fun.