Thanks, Kye. The AF is like magic coming from Panasonic all these years.
The first Sony lens I tried out in the shop, the 24-240mm, is insanely fast, accurate and silent, which is what made me decide to return the Sigma and stick with Sony/Zeiss. I'm not overly fond of zooms, so aside from the 16-35mm f/2.8, I got the 50mm f/1.4, the 35mm f/1.4 and the 85mm f/1.8. I just hope the cat's eye bokeh of the 85mm doesn't drive me nuts.
I've been doing this for years and nobody's ever said anything. They're probably just cursing me under their breath.
I don't do anything special or ask for permission. If I did, they'd probably smile at the camera, which would ruin the shot.