I thank you all for your critiques. The comments are very helpful and very much appreciated.
Using a 2x TC with the 300mm f/2.8L IS seems to bring out my paranoia at times. I kept looking at this image and thinking it looked a bit on the soft side to me. Something about the feathers just didn't look as sharp as I thought they should. But none of you commented to that effect so I will gladly accept that is was just a touch of paranoia on my part! :)