At the time, the choice was optional and I cut in the lightening holes. I consider the weight saving to be significant. I documented the weight before and after cutting in the lightening holes and posted the result here:
Be sure to cut holes ONLY in the thick spar NOT in the thinner material. I made the mistake of cutting through both and thought it would not matter Vans said it MUST be replaced. Simple case of not paying close enough attention. :