I dual hunters, and i just reached level 51 (yay). It's not difficult for PvE, but i can see the difficulties in PvP since they are a ranged dps class. As for your question, it is very successful and extremely op! Even if u dont have tank like pets, kitty pets tank just fine now since the new patch. The only thing I have to warn you is the "pet attack" controls. It is difficult to control your slave's pet to attack the same target as you due to some reason. There are plenty of macros to help keep ur pets under control, but since i only have 2 pets, I usually keybind the ' key to my main hunter as pet attack. Then I macroed everyone else the same way and since my pet on my slave is defensive mode, he runs up there the second my slave starts shooting.

As for spec...I went BM for both. Nothing beats two big red kitties. But MM would also work fine I think.

Good luck!

Chi