Yeah, it's not just size, it's where they sit. The smaller and perkier, the better for peri (which I think is what you mean by liposuction). The more they hang down or the larger they are, the better DI is for you. Peri often requires a number of revisions before it looks like a male chest. DI has scars, but doesn't usually require revisions unless you're overweight.
As far as size, if you wear a bra, B cup or smaller is usually the outer limit for peri, although it still depends on hang. If you don't wear a bra, odds are you're not bigger than a B cup anyway.
Dennis