Not only on the fight. Pets have some drawbacks like randomly dying in spellweave etc. I prefer a nightfall specc at Entity as it just outdps everything else right there
(current record 2667dps).
Something I have been wondering is, I actually was thinking of this when t5 came. With setbonuses and stuff not affecting pets I would imagine a pure nightfall specc would outdps a pet necro.. A nightfall build can achive high dps but the aggro becomes an issue sooner than on a pet necro since pets have a lot minus hate.
Will be interesting to see once I get full t6 on my necro, the extra spell penetration might do a whole lot that would prefer a dts build over a pet build.