Impersonal/Anticipatory 'It'

I'm one of those obsessive English purists, but because I'm far from being an English professor, I don't know all the little rules of English. For instance, one thing that drives me crazy is the little known rule or I think it's a rule about the use of a dummy 'it.' Technically, in the most "pure" of English, the use of any pronoun without antecedent, such as the dummy 'it,' is deprecated. But because English cannot realistically adhere to that ideal, I can accept exceptions if they are widely accepted as grammatically correct.

There are two kinds of dummy 'it.' One is "impersonal" and is already accepted, used it cases like "It is raining" where there can be no possible antecedent (or if there was, the "proper" construction would be complicated and clunky). The other is "anticipatory," such as "It is dogs who bark," where a simple rearrangement and rewording avoids the dummy 'it' altogether: "Who bark are dogs" or more pleasantly "Dogs are the ones who bark." Somewhat cursory searching on Google and the newsgroup suggests that some say anticipatory 'it' is not appropriate for formal speech/writing, but others mention no such restriction. What I would like to know is whether or not the anticipatory 'it' construction is truly generally acceptable (and not just in informal situations) and if it is really a proper, correct construction and not a clumsy bastardization.
In other words, I want an authoritative answer about this.