Digital BW, The Print

Hi, I need some clarification on mode changing from 8 bit to 16 bit. 
It's my understanding that unless the file originated as a 16 bit file 
there is no advantage to change an 8 bit (or whatever) to 16. No net 
gain. Is that right? In a specialized photoshop class there is 
instructions to convert an 8 bit file to 16 but as I recall there is 
not an advantage. Can anyone clarify? Thanks in advance.
Jack