certainly this is not the case for every woman, it’s true that most of the time
larger implants can cause more problems. A lot of this is just due to physics.
Larger implants are heavier, therefore they sag faster, are more likely to
bottom out and can require a lift sooner. However, none of these statements are
absolute, because they depend on your unique anatomy. For example, a very
thin-skinned woman without much natural breast tissue is likely to see more
problems with larger implants, while a woman with larger natural breasts and a bigger
frame may not have the same concerns. If your plastic surgeon felt these
implants would work with your anatomy and you’re happy with your new size, those
are the main priorities.
Bigger implants mean heavier implants, and these can certainly cause more problems in the long run with sagging as one issue.
I would hope you did sizing or somehow visualized what you would look like with your increase in size. And that you reviewed the potential risks of using implants of that size before having the procedure. I personally believe that life is about living and if that size was going to make you very happy, then go for it. If it does create tissue issues down the road, deal with it then with appropriately selected procedures.
Up-sizing -volume increase with implant replacement is usually a very easy and excellent improvement in the shape, feel and aesthetics of your breasts. The properly selected implant should yield excellent results. In the individual with thin lax tissues, larger implant volumes/weights can stress tissues, and with these some of the inherent palpability characteristics of saline implants (scalloping of the radial outer shell) may be more likely.
Congratulations on having undergone the breast augmentation revisionary surgery; I would suggest, given that you are fresh out of surgery, that you concentrate on your recovery. It may give you some peace of mind that the use of a 650 cc breast implant will not necessarily “lead to complications”. Assuming, that the breast implants are “fitted” appropriately to a patient's anatomical dimensions, many patients do very well with this size ( and even larger) breast implants in the short and long-term. Of course, your own plastic surgeon will be your best resource when it comes to more specific answers and/or reassurance. Best wishes.