The TNG Ferengi were so much different than DS9, I think because Picard mostly tangled with the officers on the Ferengi Alliance ships. Daemon Bok was willing to kill Picard for revenge, the Ferengi in "Force of Nature" took shots at the Enterprise when they entered the Hekaras Corridor, and in "Peak Performance", the Ferengi nearly crippled the Enterprise. However, even among the "officers", there seems to be a code that they follow making them very different from Kivas Fajo. Maybe just the rules of acquisition, but it seems a little more than that. At least one good example of that exists, like when Kazago relieved Bok of command.
The Ferengi of DS9 were all, or mostly civilians, and they definitely seemed to have a different rulebook. However, with a couple exceptions (the assassin hired by Quark in "The Magnificent Ferengi", and maybe Quark's cousin Gaila), I'm not sure that Ferengi would ever go to the lengths of killing for profit. Devious yes, but not murderers.
Kivas was so obsessed with his collection that he was willing to make an enemy of the Federation for his prize, and obviously lost. The Ferengi would more likely manipulate the situation so they came out on top but maintained the relationship.
Just an opinion...hope I backed it up with enough references :-)