based on your feedback so far, i think you would appreciate full camber for the pop and stability, but on the flipside i think you will appreciate the ease of buttering that comes with rocker, as well as extra float in powder.  you should be able to find a middleground that gives you enough of both sides.

weight-wise, pretty much everything is going to be lighter than that older board these days.

as far as stability, it's hard to say.  there's nothing like a good full-cambered deck for that, but you can certainly find hybrid rockers that are very stable.  usually a profile like the omni will give you a lot of the feelings of camber like stability, carving, etc, but it's just a little easier and slightly "looser." you may also find that with carving, it feels slightly shorter than its true length because of that loss of effective edge, but that doesn't have to be a negative.  in return, it may help with that slow edge-to-edge feeling.  it's easy to maneuver because of the slight rocker, but still powerful and grippy from the camber.

the only thing i have personally not liked about a profile like that of the omni is that it feels a little shorter than advertised (to me).  it depends on the exact board and it's not much in general, but still.  it's a preference thing, and i like the feel of full edge contact, hence i'm not totally in love with a board that feels a little shorter than i like.  i guess that's part of the reason for suggesting you slightly size up with the omni?

it's late and i'm getting a little loopy, so we can continue this later.  plus, the other helpful members are probably sleeping at present...

hybrids can vary quite a bit.. ultimately it just means you have rocker and camber in the same profile, but they can come together in a bunch of different ways.

the omni's camber is a little lower than average camber, thus a slightly mellower feel, and it extends a few inches past the binding inserts if i remember correctly.  this means you're standing on a cambered platform, which gives you edge hold, snap between turns, pop, stability, etc.  but when you add rocker to the ends of the board, it shortens the effective edge like i said.  you do lose a little natural edge hold (focuses it a little more toward the center VS the entire length of the board) and it changes the feel a bit, but we're not talking about anything too extreme.  it's just a little easier to ride, more forgiving (won't kick your ass as much if you make mistakes), and it adds float in powder which you may really love.  "a more forgiving camber" is a pretty good way to put it i guess.

i'm always a little nervous when i help people with boards (i help run a shop) because the reality is that you never truly know anything for sure.. it's more of a best-educated-guess situation.  i will say that i'm a little wary of how you'll feel about the omni just because you're used to that older stiffer board, but at the same time, so many people end up loving boards like this after upgrading from an old deck, and the omni is fully capable of being the awesome all mountain board you're after.  and if you're a half decent rider, you will adjust to anything.

personally, and especially since you said you think your 57 is a little small, i would suggest the omni in a 59.  just a hair bigger.  i think the 62 would be a good choice too, but with your desire to start heading to the park, 59 it is.  still enough to support you, not too much to hinder you.  the width will be fine for your 10.5s as well.

i think getting the proper size here is key.  what are your weight/height/bootsize stats, and how big is the board you're on now?

i would break it down like this.  if you go with the full-cambered OG, you are going to get a precise, snappy, supportive ride that holds a great edge and has a lot of energy throughout the ride because of full camber.  the omni will still ride great, but putting rocker in the tips shortens the contact length, thus giving  you a looser more playful ride, and less natural edge hold, and the pop/spring/liveliness is altered as well.  that's not necessarily a bad thing and you may still love the ride, as everything is preference on an individual basis.