Well according to a book that I read on the subject, if you are playing PL, you never raise preflop, even with the best possible hand. You don't want to chase out your potential earnings before the flop. If you go all in most of the other players will fold. With Limit however, it is ok to raise preflop, because most players will pay one bet to see the flop. In fact with limit a lot of the players will chase down a hand to the river, not realizing that those 'one bets' add up, and before you know it you are pot commited. Omaha is not a game of how much you win in each pot, but how much you keep from loosing in each pot. "Know when to fold'm"!!! Those A2 combos can be in four different players hands at the same time, remember that. A
pot split in half and then in quarters, is a loosing pot.