Upload & Sell: Off
Thanks everybody. I currently use the 300/4 instead of the 400/5.6 because of the min. focus distance and weight advantage. For the BIF picts, in my situation, I'm finding it a little short.
I always preferred native lenses, despite my experience with brand new Canons for the past few years which hasn't been that great (however the Nikon was a total calamity).
I was considering a 1.4TC, but I really don't like contraptions.
If I could get a definitive increase of quality from the current DO over the 5.6 lens, I would rise above "what the average person can afford" category. The lenses are long-time keepers, so an extra financial sacrifice is justified. In terms of weight, a 2kg "pipe" is already a monster IMO, so anything longer and heavier would be a super-monster. I don't feel I'm ready.
I never owned a Sigma. It is a very nice humming bird portrait, however I'd prefer a little more definition of the eye (which may be possible with a different PP). Please do not construe this as a criticism, but rather an indication of my personal expectations of quality level. Nevertheless, I'll take a look at the Sigma options - thanks Paul.
Just saw the new DO 400 lens patent, but from the patent to product is probably a long way. The DO technology is excellent, so it would be foolish for Canon to drop it. My experience with the first version of the 70-300 DO indicates that the mechanical design and most of all manufacturing was the problem.