Ah I see now. The bolt on look... ironically probably the quality that generated the most fans of yours, hehe! In all seriousness, this question is probably the most important one to me, however. My babygirl (avatar) is not interested in looking like a blow up doll, and my preference is the "hentai look", unreasonably big, but very "boob-like" still.
I've come to realize a few things about what achieves this, and surprisingly the implant itself isn't the primary factor. I do believe silicone makes things much easier, because even at enormous sizes they seem to "slouch" a little easier than overfilled saline (look at tunisbabe, or even our friend Ariane... they do "stand up" quite a bit still, because they are and extreme profile, but they're still relatively squishy and hang nicely).
However, the primary factor seems to be pocket consistency and size. You notice identified it yourself, and I have not seen one case example of a woman who has reduced from "canteloupes" to something slightly smaller and has not achieved a much more "boob-like" shape and feel. This aspect is simply the pocket size. The fact is, most implants are soft and squishy, and given enough room, they will jiggle til the cows come home, and look beautifully breast-like (not necessarily everyone's preference, but it's what we are trying to achieve).
There is another aspect which is usually overlooked, but I believe is very significant, is the behavior and consistency of the capsule itself. In comparing augmentations of both saline and silicone, there seems to be such a variety of results that cannot be explained simply by the type of implant. It's true, pre-existing natural tissue has a large influence on the look of the outcome, but it cannot completely explain why even among small boobs, some sit high and tight, while others swing low like chariots... our skin is such an adaptable organ, that just as people can gain and lose 200 pounds and it gradually adapts to either change, so the skin will adapt to virtually any size breast implant.
What does not continuously adapt is scar tissue and supporting membranes. In a breast augmentation this growth is what holds the implant in place and keeps it from sagging until it looks like a baseball in a stocking! Strangely I find surgeons do not discuss this aspect in enough detail for people like us to understand, but many things affect the consistency of this capsule, such as smoking, amount of massage, and the individuality of each woman's body during the healing process. My personal suspicion is the vast number of young pornstars with around 500cc who end up with "hard" looking boob jobs are most likely just not massaging enough and deeply enough to keep that loose and "natural" behavior of the pocket.
We all know of the "complication" of capsular contracture, but if you think in medical terms, this is really just a way of categorizing an extreme degree of these factors. If a woman's body happens to like producing thick, solid scar tissue, and she happens to smoke on top of that, and then maybe the swelling and pain discourages her from massaging deeply, she will almost inevitably end up with some noticeably degree of CC and may or may not need a surgical "reset". Of course the good news is there is still hope. She cannot alter her genes, but she can quit smoking and dedicate herself to a rigorous massage and stretching routine.
When we embarked on this adventure, we asked Pousti to produce a "semi-natural" look with 700cc for her first time, and he definitely created pockets with enough room to begin with, and now that she is fairly settled, the girls move around a lot and hang fairly well. However, she is 10 months out and it took a long time to get where we are now, and to start seeing true "fluff" action as well. She uses a heating pad and massages herself but as I work overseas at the moment the real, effective massage is only for short periods. For her next surgery I intend to be sure my work situation enables me to provide that "service" for at least the first year, because I think it's critical in producing the outcome we desire. She did quit smoking, but cannabis is another story, and combined with her genes I suspect we are fighting a battle with nature, but based on her progress, we are winning.
So what is my advice? I think once you've gone silicone and the surgeon has produced a quality pocket, the only thing left is to nurture the perfect capsule. Since this new tissue is primarily collagen, I recommend a heating pad. If you are familiary with Bikram yoga, you may know that a temperature of 105 F is the point at which collagen begins to soften and this is extremely useful in developing flexibility. Just as in yoga, having squishy boobs depends on flexible connective tissue. Heat plus deep digital massage, as well as stretches where I pull together, up, and down, are the best way to enlarge the capsule and keep it just loose enough for natural movement. I am also planning to develop a method of using light bondage (rope) in order to assist in this. We aren't really into S&M but carefully employing some bondage wrapping is a sure way to stretch breast tissue and of course the capsule.
Hmm... I should write a book, shouldn't I. I have been surprised to find so little discussion on this specific aspect of augmentation, but hopefully we can connect people who are looking for the same "middle ground" of huge, but breastlike... anyway, Amy, with a generous amount of tissue and skin, you will probably have little trouble keeping the behavior of your 1100s, if only because the implants can move around and gravity helps stretch them constantly. I really think you are safe going any size you wish, but I recommend going silicone and taking the aftercare to the next level. There are so many girls here trying desperately to achieve that inflated look, that it's clearly not something accidental, or that one gets inevitably at a certain number of ccs. If anything, let me say I wouldn't worry about it happening without trying.