Cochlear's website is full of information about BAHA.
But from a very personal experience, more benefit than negative. The only negative is that pain in the screw has to be assessed very quickly if persisting after 12-24 hours.
I have a better stereo hearing and I can even locate sounds in inside places like home, hospital, restaurant etc... It wasn't expect from my ENT doc with a prelingual SSD.
But since I don't know which kind of deafness you have, I can speak only from personal experience, which may not apply to you.