You can pull an entire quest area easier with a ferocity pet, and master’s call typically doesn’t do much when leveling.
The movement speed can be a help, but overall it probably won’t matter if you’re using heirlooms. A scalehide is downright invincible even once you get to quest hubs that aren’t faceroll though.
I definitely get the clear benefit of leech. I guess from a time-spent scenario, I’m wondering what would be quicker over the long haul - moving faster from mob to mob, vein/herb node to vein/herb node, or mass leeching? Wondering if leech is even necessary when you’re decked in enchanted heirlooms.
I will try out using the cunning pet for the speed boost, but if I notice struggled in mass pulls, I’ll switch back to Ferocity.