I do not have one personally, but I have several buddies that do and have shared many stands with them and used their guns etc.
They are awesome for many different reasons. I plan on getting one myself. Killing more coyotes is not one of the reasons I want one though. I kill just as many multiples as anyone with my high boom gun. Some coyotes turn inside out when you shoot a suppressed gun just like with an unsuppressed gun. Some dont notice the shot, just like with a high boom gun.
Lots more pleasant on your ears, and your buddies/dogs ears. Also you hear the meat report when you hit one, which is cool. You can shoot without hearing protection. These are reasons to have one, killing more coyotes is way down the list. Granted, most people that have went to the trouble and spent all the money want to think it helps with multiples. Well, of course they would.