I recently updated the firmware in the Z9 and last week received the 1.4x TC. So decided it was time to give them a go. I know it's poor practice to change multiple variables at the same time but I perform commensurate with the pay 
For those not wanting to read the rest here's the punch line.
Overall impressions with Z9 fw 3.0
- Animal detect AF zeroes in on the eye much faster. Most times it went through the progression from largest to smallest focus box almost instantly.
- Eye detection works with bird much smaller in the frame that before
- Eye detection works much better on BIF
- AF is sticker overall
- Much less prone to grab a busy BG
- When it did grab the BG could often be brought back by releasing and re-engaging the AF-ON button without having to resort to the MF ring
Overall impression of the 400mm 4.5 w/1.4x TC(Caveat: I've not shot any BIF with the bare lens for comparison)
- Really fast AF. I'd say no noticeable difference vs 500mm PF/FTZ
- Excellent IQ
The conditions for this test were pretty demanding for both me and the kit. We have a city park with a pond in it where a couple of hundred mallards and a few geese winter over due to people feeding them. There is a parking lot about 15 feet above and a 100 feet distant from the pond. I stand between the pond/parking lot and wait for someone to come along with a bag of bread for the ducks. When that happens the shooting is fast and furious as the ducks jump up from the pond and fly right by me headed for the handouts. There's only a second or two to find the bird in the VF, activate AF, and squeeze off a burst. It's fun
First test: eye detection on static subjects. Following are all full frame images to give a sense of range/size in VF.
Shooting handheld, AF-C, wide area S, animal detection on
1) Of course this better work. The eye was detected so fast that there was no indication of the camera going through the steps of body/head/eye as it zeroed in.
2) A little farther away. Definitely grabbed the eye. Again no perceived stepping through the boxes as the camera zeroed in on the eye.
3) Farther yet. Couple of ducks in a small pothole separate from the main pond. This time the larger box appeared on the duck briefly then the smaller box on the head. The tiny box on the eye never did appear.
OK BIF time. Shooting handheld, 15fps, AF-C, wide area L, animal detection on
Presented full frame again to give a sense of range.
4) 13 frame burst. The smallest focus box never appeared. They eye was sharp in 10 of 13 frames. Two frames focus appeared to be on the breast and the last frame nothing was in sharp focus though may have been motion blur.
5) Second to last frame of sequence.
Against a busy BG.
6) Unfortunately due to the nature of this particular location I didn't get an opportunity with birds smaller in the frame against a busy BG.
7)
8)
For those not wanting to read the rest here's the punch line.
Overall impressions with Z9 fw 3.0
- Animal detect AF zeroes in on the eye much faster. Most times it went through the progression from largest to smallest focus box almost instantly.
- Eye detection works with bird much smaller in the frame that before
- Eye detection works much better on BIF
- AF is sticker overall
- Much less prone to grab a busy BG
- When it did grab the BG could often be brought back by releasing and re-engaging the AF-ON button without having to resort to the MF ring
Overall impression of the 400mm 4.5 w/1.4x TC(Caveat: I've not shot any BIF with the bare lens for comparison)
- Really fast AF. I'd say no noticeable difference vs 500mm PF/FTZ
- Excellent IQ
The conditions for this test were pretty demanding for both me and the kit. We have a city park with a pond in it where a couple of hundred mallards and a few geese winter over due to people feeding them. There is a parking lot about 15 feet above and a 100 feet distant from the pond. I stand between the pond/parking lot and wait for someone to come along with a bag of bread for the ducks. When that happens the shooting is fast and furious as the ducks jump up from the pond and fly right by me headed for the handouts. There's only a second or two to find the bird in the VF, activate AF, and squeeze off a burst. It's fun
First test: eye detection on static subjects. Following are all full frame images to give a sense of range/size in VF.
Shooting handheld, AF-C, wide area S, animal detection on
1) Of course this better work. The eye was detected so fast that there was no indication of the camera going through the steps of body/head/eye as it zeroed in.
You can only see EXIF info for this image if you are logged in.
2) A little farther away. Definitely grabbed the eye. Again no perceived stepping through the boxes as the camera zeroed in on the eye.
You can only see EXIF info for this image if you are logged in.
3) Farther yet. Couple of ducks in a small pothole separate from the main pond. This time the larger box appeared on the duck briefly then the smaller box on the head. The tiny box on the eye never did appear.
You can only see EXIF info for this image if you are logged in.
OK BIF time. Shooting handheld, 15fps, AF-C, wide area L, animal detection on
Presented full frame again to give a sense of range.
4) 13 frame burst. The smallest focus box never appeared. They eye was sharp in 10 of 13 frames. Two frames focus appeared to be on the breast and the last frame nothing was in sharp focus though may have been motion blur.
You can only see EXIF info for this image if you are logged in.
5) Second to last frame of sequence.
You can only see EXIF info for this image if you are logged in.
Against a busy BG.
6) Unfortunately due to the nature of this particular location I didn't get an opportunity with birds smaller in the frame against a busy BG.
You can only see EXIF info for this image if you are logged in.
7)
You can only see EXIF info for this image if you are logged in.
8)
You can only see EXIF info for this image if you are logged in.
