You have first to delete sh and rename sh0 to sh using adb in RECOVERY!
In this ROM sh is just a link to busybox and that is stupid, because updating busybox is impossible this way!
If you have done this one time, you can use every way you want ...
There is no "real"
With hardlinks, every file is the same!
Even hard links have a source, a file it is linked to.
EVERY file it is linked to! You can delete all but one, no matter which one, and the file will still exist!
You can copy it to /system/xbin, but there is no need. One sh in /system/bin is enough as long as the one in /system/xbin is removed!
Maybe you need a new sbf, after the new phones came out