For those wondering about how the new 1.4TC will perform, I can't answer that yet, but I can give examples of the K3+1.7AFA+DA*300. Stationary pelicans were shot with AF-S and SR on, flying pelicans were shot with AF-C and no SR.
The next images are part of a 30-shot sequence showing a White Pelican that has one leg banded and has large green tags on each wing. Here are the creation times for those shots:
an average of 6 fps over 30 shots using AF-C. The first 25 shots were all in focus, but only 2 of the last 5 were in focus. However, by that time the 1.7AFA probably had hit its maximum adjustment range as the pelican moved farther away.
The wing tag reads:
The leg band number is 0759:
I'm looking forward to shooting these pelicans again using the new 1.4TC so they won't be able to fly out of focus range.