Great post and it's really fascinating to hear about your transplant.
But since you are writing about how your hearing device has bluetooth I'm wondering about the possible downsides of real bioengineering.
I mean... currently if somebody were to hack your bluetooth for example (I know it's unlikely but I don't think it's impossible) he could make you hear anything in your head. A loud unpleasant noise, his parents having sex or anything at all. Of course currently you could just deplug your external device but what if you had a real transplant that could provide enough energy from your body to not be removable?
Imho it's probably hard to make a closed enough system that it's not vulnerable to the outside and still totally controllable by you. So while I get the advantages of something like a hearing aid you have or a nfc tag in your skin (because that doesn't pose a real threat to your health) I would be a little careful with anything that really goes inside you and could possibly be controlled by the outside.