i just had genio and have permanent impairment.
Are you sure its from the genio and not from the BSSO? IIRC the way you described it seemed like it would have been a product of the actual bone split, which takes place in a rather uncontrolled manner (if you watch some videos of bssos being performed, youll see what im talking about.)
Genio alone has a SUPER low risk of injury to the mandibular nerve, like basically unheardof, unless the surgeon was rather careless. Rather, if you believe your nerve injury was genio, it would be damage to the mental nerve formen, which provides some sensation to the lower lip (but not motor function).
I really do wish chin wing was a more common procedure. If we could see all the european surgeons on a board like RATEMDs with hundreds of peoples experience and ratings, it would be much easier to make an informed decision and the surgeons practices would likely benifit. Word of mouth is only so reliable...