I succumbed to NAS and picked up a 80-200 f/2.8 AF-D push-pull for my D7100, and was wondering if a Kenko Pro 300 2x DGX may be a feasible way to get to 400mm for BIF or static bird shots, while preserving AF. I know it will work in theory, but am hoping to get some real-world feedback from fellow Nikonites who've been brave enough to try this 2x TC with this lens in the field. Sample images that highlight the pros / cons of this combo will be greatly appreciated. Thanks in advance!