Copper will remove sulfides from the final product- that is the main benefit from a copper still.
The more copper that comes in contact with the wash during the distillation- the more sulfides will be removed. If you are running a stainless still I always recommend packing the column with as much copper as possible. Copper scrubbers work really, really well at helping if you are running stainless. The other option would be to run a stainless pot and a copper column- packing the column as well
Kyle over at clawhammer wrote an article on packing his columns-
http://www.clawhammersupply.com/blogs/moonshine-still-blog/7486102-distillation-column-packing-for-higher-proof