I know what you mean..
my first mirrorless was a Panasonic gx8.. and it had the silent mode and who knows how many fps in silent mode .. while I personally would never use 20fps , a quick 3 or 4 pic burst does come in handy (for me)
but at first I ended up with tons of images that I didn't need to shoot as I would press shutter longer than I needed as I was never sure when it was shooting or if it was shooting
but for those that do need those high fps .. that a9 link seems like no visual lag at all
I wish there was an easier way to try out Sony cameras since their Sony store nearby shut down. $7500 to replace the Fujifilm XT2 + 50-140 / supplement the 1DXII + 70-200. Hrm...