I know hyperzooms are not the best quality, but how bad are actually these 2 lenses? I currently cover that range (and more) with 17-40f/4L, 50f/1.8 and 70-300 IS DO. I'm looking at getting some all-around lens for hiking, etc. How bad is the Sigma 18-200 compared with the 70-300DO? How about the Tamron?