The whole point of LL is to make you taller without your shoes on, and without making you look unnatural in any way (ideally speaking). But, with these implants, I guarantee that people are going to notice a foot with a built-in 3 CM+ high heel. And if you're in an environment where lots of people are around you while you have your shoes off, like at a pool party or the beach, people WILL notice your misshapen feet. Even if they are all blind or lost their glasses (and you didn't know they were visually impaired) and they somehow didn't notice, you'll be nervous (and hence awkward) the whole time just hoping that they won't notice, and you won't enjoy your height on account of your nervousness.
Plus, imagine running with high heels. That's how running with implants would feel. Basically, as with a case of LL gone wrong, you'd never be able to run again, as long as the implant stays in that is. Please don't make a case that it's possible to run in heels. I've seen too many b*tches fall instead of look slightly less tall.
You'd be better off taping lifts to your feet. Sorry to anyone with the naïveté to consider this a viable option for height gain, but heel implants have "terrible idea" written all over them.