Thanks Jayson.....I really ran up a big water bill this month
Still fiddling with the 300mm f/2.8L + Version III 2X TC.
ISO 3200 (very cloudy here today)
f/5.6
1/200
Using the 1D MKIV this combo focuses very fast, almost as if a teleconverter is not on the lens. The images are not quite as sharp straight out of the camera and they are a little noisier compared with the Version II 1.4 TC but they seem to sharpen easily enough and the noise isn't too objectionable. Also keep in mind I have done no AF microadjustment.
The overall performance in my opinion so far is excellent and certainly a viable alternative for bird photography. I will continue trying it and hope to get better conditions so I can use a lower ISO. I will also do some test shots with the 70-200 mm f/2.8L IS USM soon.