I have 2 major thoughts for those using the new TAP.
1) It works much much better on an a7iv than the a7c. I was not getting the results that some of you were reporting and/or indicating (though it's subjective with what working "good" means, and what lenses are used).
Used the a7iv and a7c with the new TAP using the 35/2 Ultron and 50 Sypotic, both in AF-C, Eye-AF (Human) with Expanded Flexible Spot, Wide or Center and with "AF Tracking Sensitivity: 3 (standard)."
The A7iv was considerably better in all regards--quicker to acquire the subject, quicker to lock once found(go green), racked back and fourth between near and far subjects faster and very little fluttering comparatively. The CV 35/2 is poor on the a7c, but would be quite usable/not near as crippled on the a7iv. The Syoptic is quite good on the a7c (like the 4 other fast 50mm's I have used) and another level on the a7iv. The a7iv allowed for great AF and tracking outside the dead middle of the frame as well. For serious TAP users, the a7iv is real consideration.
2) On the a7c, the "AF Tracking Sensitivity" in the menu makes a large difference. And its lens dependent. I can barely get the a7c to lock onto a static decently contrasty subject in normal light with a couple lenses, but changing the "AF Tracking Sensitivity" greatly reduced the fluttering, and decreasing the actual time to lock and go green. That setting makes a very appreciable difference on nearly all my lenses I've tried.