Has anyone compared these 2 lenses? Even though I like my 300/4, would like faster glass in the 300mm range. I know the nikon 300 2.8 does well with a TC, what about the Tamron? I think my Kenko TC will also woek on the Tamron. I know there is a huge price difference, and I am curious of how "bad" the Tamron really is for the money. Any input?