I want to purchase one... I am usually up on all of the lenses and camera bodies, but tele-extenders isn't something I have delved into. I shoot a lot of sports and I am not rollin' in the dough so I don't have the lenses I'd LIKE to have... I am still working with a 70-200 f/2.8 as my main. So... I really would LOVE to go with a 2x, but... I also know I have read that the 2x isn't so hot... Help? best bang for the buck? I do not want to compromise on sharpness if I can get away with it. The compromise on f/ I can do in most situations, so I am willing to try it!