I am not a scientist, but I do like to brine. But, regardless whether it adds moisture or tenderness (which I think it does), I load up my brine with fresh herbs from my garden, and there is NO doubt that I taste those herbs in my rotisserie cooked chicken. There is also no doubt that my chickens are moist and tender.
The moist and tender part could possibly be a fluke, but I know what my fresh herbs taste like, and I taste them in my chickens. So, something good is happening in that overnight brine.
CD