I'm not sure what you mean by "inverted conditional". Is it this?
1) I'm not as sure of that as your brother would be. <-ordinary order
2) I'm not as sure of that as would be your brother. <-inverted order
If that's what you mean, I would agree that the second one is slightly more…well, maybe not formal, but fancy. But not always; there are situations when it's actually better, even in informal writing.
James J Kilpatrick died recently, but until a few years ago he was the writer of a syndicated weekly column entitled The Writer's Art. I read it enthusiastically, and during the last five or ten years of his life sometimes emailed him comments, which he was usually polite to respond to. One of these was on this subject, which I include here:
I write respectfully to take exception to the court's ruling as recorded in
A brief quote:
«….Jack Carpenter of Alexandria, Va., who complains of a different "did." He cites The Washington Post: "To avert a major benefit cut, Medicare will require a significant tax increase. But Mr. Bush will not say that, any more than did Bill Clinton."
«"Any more than did Bill Clinton"? You ask, what kind of syntax is that? Lousy syntax, the court responds. To avoid such a clumsy construction, writers should take refuge in repetition: "Mr. Bush will not say that, any more than Bill Clinton would say that."»
Let's notice briefly and discard as unimportant your accidental miscorrection, which should have read "Mr. Bush will not say that, any more than Bill Clinton said it" (or else it fails to parallel the Post's original). My principal objection is this: I've never gotten the impression that "…any more than <helping verb> <subject>…" is clumsy. "You wouldn't have thought of it that way any more than would I" sounds fine to me, if a bit formal; likewise "my ideas on the subject aren't any more authoritative than are his". Mr Carpenter's putative Horrid Example is actually no more horrid than are the examples just mentioned. If he dislikes the slightly formal tone, he need only restore the normal subject-verb order; and even that (although it often sounds more natural) is no more CORRECT than these are.
Furthermore this allegedly clumsy construction is sometimes necessary, for example when the comparative subject takes up more than a word or two. Surely you would have rejected the complaint had the Washington post written "But Mr Bush will not say that, any more than did his predecessors Bill Clinton and, in previous administrations, Presidents Jimmy Carter and Richard Nixon". Putting the verb after all that long-windedness would have obscured the meaning, and it certainly wouldn't have made it sound any more natural than the much simpler and clearer method of keeping the verb nearer the comparative "than" would.
Ah, I see. Well… I don't know that it's necessarily more formal. But I would say it's a slightly older form; they don't use it as much nowadays, and when they do it's always in print—I mean, I don't think I've heard anyone say it aloud.
But then, older forms that nowadays appear only in print kind of are more formal, aren't they? Someone else say something, here; I suspect I don't know what I'm talking about.