You might have heard to always underexpose by 2/3rds of a stop when shooting in broad daylight. Again, we here at NYC Photo Safari believe that ALWAYS is a strong word.
In broad daylight you are likely to have a dynamic range issue. This means that the bright areas will be too bright and the shadow areas are too dark. If you underexpose your photo, you are likely to lose everything in the dark areas. And it is more difficult to recover the dark areas than it is the bright areas.
The digital media is more capable of holding information in the bright areas than the dark ones. In other words, during post production it will be easier for you to get details out of bright areas that look blown out while it will be very difficult to do the same with dark areas. If you have dark areas that have dropped out and you try to bring them up, you will find that the area in question and potentially the whole image will be a little bit muddy.
So, as a rule of thumb, this is not likely to work the way you think it will. So go with a neutral exposure and leave well enough alone.