If I can find a piercing that doesn't always move, I may think about it. We will see. But I will definitely make sure it works before I decide to use it.
If you take any piercing set - you should be able to parent it directly to the right/left pectoral which should then follow accordingly.
Alternatively, something like this - "Alternative Piercing Pack for G8" - these follow bones AND pose morphs like breasts up/down correctly.
Also make sure with all piercings you 'memorize item' with both the container and the object, so when moving figure around and using stuff like restore they dont jump to 0,0,0.