[Balanor]

I see I missed this question - apologies. To answer it though; no, you do not get more notoriety for selling an enslaved slaver or assassin. In fact, it will probably be more beneficial to you to kill them instead as you get increased XP and gold from each, similar to what you'd receive if you had successfully completed an assassination quest:

-XP for killing assassins and slavers sent after your characters has been significantly increased, in addition to the amount of gold each carries as well. Thanks go to Animayhem for this idea