Griffin,
I plan to purchase the Canon TC II 1.4X. I have read that AF does not work below f8, but I have also read that this can be overcome by taping one or more of the contacts on the TC. I have also heard that it doesn't work well in low light conditions. Am I incorrect on these?
No, you're not incorrect. You will most probably find out that with the 10D you will end up focusing manually most of the time with that combo. Manual focusing is not necessarily a bad thing, though.
My 10D doesn't like focusing with the 300mm f/4L and 2x Extender II, but it still makes a great manual-focus 600mm f/8L... 
I have taken close to a thousand images with my 10D and taped Canon 1.4TC and my 100/400 IS lens. Auto Focus works very well for me.
Example: This was just a grab shot as I saw the bird out of the corner of my eye.
http://homepage.mac.com/meckstein/post/peli4.jpg
Another Example:
http://homepage.mac.com/meckstein/post/flight.jpg
I have the 2x extender. I cannot get the AF at all with 100-400 combination. which contacts did you tape up to make the AF work?
