Anyone with experience using this EF-S lens? I don't hear much discussion about it here, and I can't seem to find a shop around me that has one in stock to play with. I'm weary about spending that much money on a lens online without trying it first. How is the feel and build quality compared to L lenses? What about optical quality compared to similarly priced L lenses? It has the advantage of lighter weight, IS, and a more crop-friendly zoom range than the 24-70, but doesn't seem to have metal construction or weather sealing. I guess what I'm looking for is whether or not it's worth dropping that kind of money on.