I have used their forms in the past myself. From my experience and what is clearly stated on their website and product description, is that the only difference in them is the thickness of the tapered edge. There maybe some concern with the "thick" edge of the form being more readily visible, and thus it being more readily noticable that you are wearing breast forms. THe "thin" edges supposedly taper off better and thus it becomes a lot harder for people to notice where the breast form ends and your chest begins, making the forms look more natural.
That being said having used both Real Breast, breast forms and Aphrodite Breast forms, the risk of other people noticing the edge is minor, except if you are really wanting to show a lot of cleavage. And then, the issue even with the "Thin" edge is getting the edge to stayed glued down and thereby flush and flat against your skin. But betting the proper amount of adhesive right up to the edge is difficult at best.
But from a more practical and realistic perspective in regards to having other notice your forms for what they are is the coloration of the silicone compared to your natural color that day. IT is nearly impossible to get the silicone to perfectly match your skin, without the use of makeup.
Additionally, the One major problem I had with my "Thin" Real Breast Breast Forms, was that the edge had a severe tendency to curl under after taking them off, and stick to itself. THis problem became more and more prevelant, the more I wore them. And at some point it started to deform the edges, which made it harder to get the breast form to lay completely flush and blend into my chest wall.
