I have a pair of Snoqualmie Pass tires on my road bike, set up tubeless. I absolutely love them, but I got a small cut on the sidewall of the rear tire. The tires still have a lot of life in them, and, considering that they are not so cheap to replace, I decided to try repairing the cut.
[Update 4 months down the road – May 2021] The repair is holding just like the day I made it.