Doktorelmo

It is possible, there's the SM/DS (31/21/0) specc, where you sacrifice your pet to get a huge buff for 30 min, then you have to sacc it again. Saccing the succubus for example grants you 15% more shadow damage, which is huge, saccing the void walker grants you 3%hp/4sec which is nice for farming. It is definitely viable but i think with less gear the pet speccs are better.