Perhaps not the exact answer you are looking for but this upgrad would give you about the same amount of weight savings (or less) that taking a good cr*p before riding would provide (+ your wallet will be a little lighter if you ride with one). While not implying you are not in-shape, You would seriously get more performance out of becoming fitter than you will ever get out of upgrading from what you have to what you are looking at. When one references "savings" in concert with weigtht there is usually an idea of performance benefit in mind. The weight difference between the components you referenced do not really add up to any real " savings" or performance benefit. An area the you might want to consider when upgrading cranks is stiffness of the arms and chainrings and then look at stiffness in comparison to weight, but this assumes that you are riding in such a manner that crank/chainring flexibility manifests as a concern. If this was a concern, and I applogize if this sounds snobish, one would be considering an upgrade to higher tier of componentry because while both tiers you referenced are good quality, neither would be considered for high performance riding where weight and stiffness might be an issue.

-j