Thanks for your opinion. It's interesting you mention the 400 mm canon prime. My canon shooting buddy bought this lens about 3 months ago and it is now his main lens for birding. The 100-400 zoom is too soft for him and he is happy with the reach. No VR but I thought over 1/500 sec VR is not too effective if at all. I guess I'm into a whole other subject now. For me I'll probably stick with my 70-200 and 1.7 TCE If I somehow develop a passion for this type of photography and want to really get into it I will have a few choices, get the D7100 and shoot with my setup or get a 300 4.0 and see how the 7100 handles this and my 1.7 TCE. Still less expensive than this lens.
"Cameras and lenses are simply tools to place our unique vision on film. Concentrate on equipment and you'll take technically good photographs. Concentrate on seeing the light's magic colors and your images will stir the soul." Jack Dykinga