You'll know by now that I don't believe in "rules" in writing, and point-of-view "rules" are some of the most discussed/agonised-over/struggled with of the lot. Jauss's exploration of point of view and distance is so persuasive that even people who are looking for rules are brought to agree that there's no inherent reason why a first-person narrator can't narrate stuff s/he can't see or wouldn't know. If you follow Jauss, though, you could write things which "break the rules": any individual paragraph may look very like sheer incompetence. So what's a writer to do? You may know why you did it, but what if an editor/agent just tosses your work aside as incompetent?*
The truth is that you can do anything, if you do it well enough, but it's not a truth which gets you much further. Any agent/editor will say that the novels they take on or come close to taking on are the ones where they stop noticing technical issues and find they're reading for the story. Teachers and competition judges say the same. And most agents (I know, I've asked quite a few) would agree that they've got authors who do exactly what they've just said they reject: the writing just works. Yes, 80% of men/women answering a survey say they're looking for a partner who has long legs or blonde hair or a sense of humour. But, actually, lots of short-legged, dark-haired, nice-but-not-terribly-hilarious people do seem to find partners, because what actually makes people fall for each other is much more subtle than that.
Fundamentally, within the very broad spectrum of techniques current in early 21st century fiction writing, you should be using the ones which serve your project best. What publishers want is a cracking story, crackingly told. In one sense, they don't care how you do it. If it works best in third, they want you to do it in third. If it works best in first, they want you to do it in first. If its natural length is 141,000 words, they don't care that 90% of books in that genre are around 110,000. They only notice if 30k of your words are surplus to requirements.
If you think a certain technique might be just what the project needs, but you don't dare do it, then there is the option to not do it.If it's just one possibility and there are others, then you might as well stay safe: in the case of the omnisicent first-person narrative, using third person instead, for example. But first-person-omnisicent might be the thing which makes the book really, really work. It might be the thing which raises it head and shoulders above similar but more "rule-keeping" books, or it might be the only way to make the book work at all. Put it this way: an early version of The Mathematics of Love was rejected by an agent because she doesn't like parallel narratives; she feels they never work and that they're therefore hard to sell. (And she has a point - various bloggers and Amazon reviewers either didn't get it, or hated it when they did.) But it was the only way to make the project that was TMOL really work, so I stuck to my guns, got more feedback and made the paralleling work better, and ended up with an agent who loves them and did sell TMOL. And, incidentally, I learnt a lot more about writing along the way than if I'd meekly cut one of the halves of TMOL for good.
But you need to do two things: first, be absolutely sure that this is the best and only way to make this project really work. And, second, you need to be absolutely sure that you can handle your "rule-breaking" technique: that the logic and feel of it is in your writerly bones. That's not just so you don't make basic errors, but so that you can be sure you're using it to best advantage. It's like learning to punctuate: you need to be able to understand but also feel the grammar and rhythm of a comma, say, so that you use it not just correctly but expressively (which might mean "incorrectly"). Only then will the technique and the project fuse completely, and only then will the professional reader start being a real reader.
And no, I can't promise that you won't get a rejection on the grounds that you've "broken" the PoV "rules"; some professional readers are better at reading for rules than for story. But really good writing doesn't come out of playing safe, does it?
*I'd like to think that a teacher would have the perceptiveness and the time to work out whether, in this case, it actually works. I know that I quite often find myself writing "Normally, I'd say don't do this, but here...because..." But that takes more time and energy than either crossing it out, or letting it by.