So, I know topic's like this have been discussed at nauseam, but I have a dilemma. I own the Nikon 18-200 f/3.5-5.6 VR and love it as a great all-purpose lens. I get some great pictures. However, I tend to shoot a lot candids in the 70-200 range and tend to have some issues indoors requiring me to shoot at very high speeds as an alternative to using a flash. I'm drawn to the 70-200 f/2.8, but I don't know if it's worth spending $1600 to overlap what I already have - especially without knowing the if the results will be noticeable. I also shoot a lot of landscapes and really would like the 17-55 f2.8 (but I own the 10-20 sigma). Any thoughts?