A bigger issue with separating the microphone and amplifier is cosmetic: hearing aids sadly have a stigma attached to them and people are more likely to wear them if they are invisible. There is a reason why hearing aids are produced in hair colors.
Also, I found that the best way to get rid of feedback was to get an ear mold rather than using an "open-fit" mold. This is a clear separation between the speaker and the microphone and pretty much solves the problem in my experience.
EDIT: I noticed late that you addressed the cosmetic issue in your post. I don't see the elderly changing but our generation just might.
Also, I found that the best way to get rid of feedback was to get an ear mold rather than using an "open-fit" mold. This is a clear separation between the speaker and the microphone and pretty much solves the problem in my experience.
EDIT: I noticed late that you addressed the cosmetic issue in your post. I don't see the elderly changing but our generation just might.