Depends on the trader's response whether I RP with them much. I use stop or die as a demand and ussually only charge cargo unless I am really hurting for cash. (To the disappointment to other Pirates I fly with)Because I don't charge much and 90% percent of the time traders run or f1, I am quick to destroy them.
I do pirate empty traders because they are still flying through my territory. If they love life they ussually pay the VERY small amount I charge. The cost of travel without an escort I guess.