You are certainly not the only one confused. The current silicone gel implants available made both by Mentor and Natrelle (Allergan/Inamed) are stickier (more cohesive) than the earlier generation models. In addition they are described as having a low gel bleed, which means that on re-operation, the surgeon doesn't encounter a sticky mess. However if the external shell malfunctions, the gel will spread out, either within the scar capsule (intracapsular rupture) or outside it (extracapsular rupture). On the other hand, the form stable or gummy bear gel implants will never leak in such a manner.
My experience with the gummy bear gel implants is limited to three patients. One lady had silent rupture with a cohesive gel implant and wanted to limit future surgery. While she is satisfied with the low maintenance of her implants, she observes that the breasts are slightly less jiggly than her old set of implants and is planning to switch back. She elected to put the gummy bear gels in the previous subpectoral pocket. The other two patients are breast cancer patients and have been pleased with the performance of their reconstructed breasts. In these patients, the implant was placed under the chest muscle and the mastectomy flaps.
The early reports document lower rates of capsular contracture with the form stable implants. Many of the principal investigators are recommending the subfascial plane, which is essentially the subglandular plane (on top of the chest muscle). The manufacturers are still struggling with the FDA, so there isn't a clear release date for the gummy bear gel implants. You should be aware that the gummy bear gel implants do require a larger incision for placement, on the order of 5-7cm, so that should be factored into your decision. Good luck.