I'd appreciate if you guys with experience with either of these lenses would help me out. I'm debating which one I should get. I like the extra reach of the 300, but not if the quality turns to crap after 200mm. Would I be better off getting the L and buying an extender later on? Would the quality at the long end with an extender on the L be equivalent to the 70-300 at 300mm? Are there other options for this focal length that I haven't found? Thanks a bunch!