I noticed this too when I was working on a large image that only shows at like 33.6% zoom. It appears to look totally different when layered as it does when flattened. If you zoom in to 100% or more and then flatten, you see no difference at all. So it appears, to me, that layer styles are magnified when zooming out for some reason...I guess so that we don't forget that they're there This really drove me nuts when trying to figure out an outer glow for rivers on my old continent style. It seemed really dark when zoomed out but when I zoomed in it looked fine or disappeared. Why it does this I have no idea...hence I don't do outer glows for anything except text...I use an airbrush instead. Cut to the chase...it's sort of an optical illusion persistent in the zooming...it looks fine at full size.