So i did a long session (~200 photos) and the number of blurry pics are around 30, these includes user errors, slow shutter speed, slow AF, kids move too sudden...
In conclusion it's around 10-15% AF's fault. It's totally acceptable for me, this new way of shooting is a relief, I just compose and trust the camera to detect the face and focus correctly, the downside is fast shooting is not possible, i have to wait for the mirror to go up after each shot for the liveview to be available for the next shot. But for now, that's good enough
PS: almost all shots are shot wide open (f1.8) so if close down at ~f4 the results will be better for sure. I'm just obsessed with bokeh in my pics