@Altovato The friend safari has a 1/512 chance to find a shiny, and that's with/without the shiny charm. It's a good place to go to get specific pokemon or if you don't have a shiny charm. I believe those are the same odds when you're chaining while using a dexnav as well, but I'm not sure. Overall it's just a good place to go if you want a specific pokemon as there aren't many others in the safari and the odds are pretty good! Plus there's no "chain-breaking" or anything, you just encounter pokemon till you find a shiny! :D
Found a shiny? Talk about it here!!