No need to try to convince me, I am just reporting a totally unbiased feedback from someone who has zero pre-existing brand or technology preference. Granted, he tried that a7rII but the a9 is too expensive for him.
To your question, I have myself not tried the a9 yet either. I am personnally not interested since it is overall IMHO mostly a downgrade from my D5 for my action photography needs centered about AF performance on moving subjects with pro grade tele lenses. I may have added one to my line up had it been more affordable, but not at its current price point. I have much better ways to spend 5,000 US$ + lenses cost, starting with my new packraft. 
Cheers,
Bernard
Definitely a downgrade for most action photography - but that's due to the lens lineup rather than the body.
I'd say the body itself represents a modest upgrade from the D5 - similar AF tracking capabilities (I couldn't tell them apart when using them - both tracked more-or-less perfectly), the addition of the very-useful eye AF and a few more megapixels. It probably gives up some durability (the D5 is built like a tank) but weighs half as much and has fewer mechanical parts that can fail in the first place. It has near-identical performance at high ISO (better at some levels, worse at others); it has better low-ISO DR, but that is of little consequence for action photography.
I never expected the A9 to be that good - I expected 5D3- or 5D4-level AF performance, with mirrorless only catching up to the dedicated action cameras in the next iteration. But Sony outdid themselves with advances in mirrorless AF technology (and, equally, with EVF performance).
But, with no long, fast lenses - 400 f/2.8, 500 f/4, 200-400 f/4, etc. - it's currently more-or-less unusable for serious wildlife or field sports. The only option is the newly-released 100-400, which, while looking great as a general telephoto lens for landscape and other use, and suitable for the occasional animal or sports shot, is neither long nor fast enough for dedicated wildlife or field sports use. So, for now, the 1Dx2, D5, D500 and possibly 5D4 and 5Ds (if you need pixel density more than frame rate and ultimate AF performance) are your only real choices for sports and wildlife. This is changing - a 400 f/2.8 or 400 f/4 is supposed to be coming at the end of the year - but, until then, the A9 is relegated to event, wedding and photojournalism roles, which it does very well (better than the 5D3/5D4 and D750, which previously owned this sector - eye AF and real exposure simulation via the EVF make a big difference here).
If the D850 delivers AF-wise and keeps up with the current action bodies in the ISO 3200-12800 range, it will likely blow all of them out of the water as an action camera, becoming the preferred model unless you absolutely need 14fps (vs 9fps) or live at ISO 25600 and above.
