Will you use SL voice for the majority of your communication in world?

No because you can be anywhere on the sim and cam to someone and hear what is being said no matter how far they are from you

I might use it occasionally in special situations, but in general I view voice chat as being very contrary to the spirit of SL. It pastes a very physical and personal aspect of your RL self directly onto your avatar, which shatters the integrity of SL as a platform for the imagination. You are no longer communicating with a virtual person in a virtual world, but are in direct audio communication with a RL person. It's hard for me to explain in words, but if voice becomes widely used, it really would destroy much of the charm of SL for me.

Edit: I should add that when I say "contrary to the spirit of SL", I mean the spirit of SL as I experience it. I know that others use SL differently and for some people voice may be quite compatible with their experience of SL.

my sister in-law requires her husband (my brother) to use a female WoW character because she does not trust him. he has cheated on her so many times she feels a need for some sort of insurance. having him use a female av, in her mind, lessens the chance that he will become involved in an internet fling.