First, yes, the more charge weight you have, the more shot you'll have, with everything else being equal. But the question is what does that do for you? Anyone who tells you that more shot allows you to use a more open choke and get a wider spread and help your shooting just plain doesn't know what they're talking about. Now, you might get a couple of inches in effective pattern diameter, but in the grand scheme of things, that really isn't going to matter. And, the purpose of those long 12ga shells is really to up the pellet count WITH LARGE STEEL SHOT. With normal duck shot, these shells are completely unnecessarily.
My guess is that if you are asking that question, you'd be better off with something like a good quality round steel shot load in 3 inch 1 1/4oz at about 1400 to 1450fps. Sized and choked correctly, that load will kill ducks far beyond where you are capable of hitting them. With the money you'll save on shells, get out and shoot some clays. It'll do more for you than a case of canon fodder.
I feel slightly sorry for a man who has never patterned his gun, who has no idea how far his chosen load will retain killing penetration. But I'm extremely sorry for the ducks he shoots at beyond the killing range of his gun and load - Bob Brister