I've used 9- and 8-speed quick links for a long time. First SRAM and more recently KMC. Cost-effective when bought in multiples on a card. I try to always have a couple in the emergency repair stash I carry on all rides. Came across a tandem team on the side of the road a few years ago who had dumped their chain on a climb and had lost half of a quick link in the process. I was able to gift them one of my spares to get them back on the road.
I'm in the habit of replacing the link when the chain is replaced.