In the current World of Warcraft we live in I am not in a raiding guild. I am in a casual guild with long time friends. However I do do PVP. So now that I have established some credibility here we go.
With the many possible and completely viable spec's in PVP today it can sometimes be a bit overwhelming. And one of the big problems is how far to go in to the Demonology tree of your main one. Know my current spec is 0/17/54 which allows me alot of versatility with my pet because I have Master Conjurer, Fel Domination and Soul Link. This makes it a lot easier in arenas to compete against many different teams. However before that spec I had a 0/14/57 which gave me Empowered Imp but I lost Master Conjurer and Fel Domination. Now this spec is alright for battlegrounds were you can 1 hit people but in 1k plus rated arena match's you start to loose that versatility and find your self being torn up by rogues and not being about to out dps priest and mage shields which now are taken of with Fel Hunter. So my suggestion to you is that you keep the 0/17/54 for Arenas because it will help you compete.