If you're into PVP ... I suggest you stick to marksman for now (Whichever one puts all the stats on you - not the pet)
As a rogue it sure is a pleasure picking off hunters who spec everything into their pet with beast mastery. All you do is blind the pet and klap the hunter 6-love. By the time the pet gets near its game over.
In PvE it works fine to spec the pet, but in PvP you're fighting people. I've taken out 2 hunters (same level & +1) at the same time with my rogue on the thousand needles racetrack due to this same reason...and this is my 1st char - only been playing for a month and a bit now. *yes yes i know i know - if there's no screenies it didnt happen, you'll just have to believe me for now*
Sap/kidney punch 1 + blind pet + kill hunter ... repeat. Even when the pets did come close, Evade made me dodge most klaps.
If I had a hunter I'd put all my talent in the l337 hunter tree and just use the pet to pull aggro. That's just me. I suggest you go read up on the
www.wowhead.com forums... there are TONS of okes asking opinions on their builds ... you'll soon get an idea.