There are those who say side slappers increase accuracy because the falling hammer kinda torques the gun when it hits. I dunno 'bout that. Mule ears don't do that. :idunno: If that effect exists, it is very negligible. I know some bench shooters like the side slapper a/ka/ mule ear for that (supposed) reason. They do send the flash directly into the main charge and that could be a good feature.
There used to be a rifle produced by Bob Tingle (now deceased) that was well thought of. His side slapper is currently highly desired by many. If I see one for sale, I would buy it.
In short, if the rifle is in good shape and you like it and the price is right, grab it and enjoy.