I'm not really much of an omaha player, so take this 'advice' sparingly.
I've recently been playing a bit of PLO SNG's and feel that raising when the blinds are low in proportion to stacks, it is absolutely essential to raise preflop if you play a hand, especially short-handed. You MUST be able to make a raise on the flop that will scare someone. I know the technically it shouldn't matter because of pot odds, but someone is much more likely to call a 1 dollar raise with horrible odds than 50 dollar raise with adequate pot odds. It's just the way it is. Also, knocking a couple people out of the pot ain't bad either.
This is one of the few scenerios where min-raising preflop in early position might be acceptable, because you aren't really trying to narrow down the field (though you just might
), you're trying to make the pot large enough so that you can narrow the field POST-Flop. As you know, omaha is more of a post-flop game, so setting yourself up for after the flop is ALWAYS a good thing!
Again, I'm not sure how this would translate to a full ring game, but it definetely works for short-handed games, where you need to steal pots to make much of a profit. The major difference I find in 6-max No limit hold'em, and 6-max PLO is that in hold'em, you steal pots before the flop a lot; in PLO, you steal after.
Just my 2 cents, but remember I'm not much of an omaha player. 8)