jerryc41 wrote:
Unless you're using low capacity memory cards, I see no reason to lower the resolution. Capture the image at the best resolution and then manipulate it later.
As for the actual loss, you'll have to experiment to find out, zooming in to see how details look.
You can always down res in post but, you can't go up. Once the data is gone it's gone. Start with the best your equipment can produce. If one spends a boat load on a 36+ megapixel camera; why would you ever ham string it by telling it to through most of the data away? Otherwise, IMO it's just a case of quantity over quality.