So Frikin' Sweet! I love it....
But I weighted that 600 when I was debating 500mm vs. 600mm.... After all the hiking I did this past year with the 500 (all over Alaska, Australia, RMNP, various locations about Arizona, and just spent a week in Yellowstone), I'm glad for the weight diference... But then again, everytime I see Tack-sharp shots like this... I wonder if I chose right... but then there are those times that even the 500mm is too close, and my friend is shooting the camera with the 100-400...
Your shot is Great, and I still love my 500 Dearly!