No one knows how it will go with Borini, but by the same token, judging him after a couple of games is ludicrous and typical of a few of the trigger happy posters on here. He needs time, he's 21, he could be great, he could be pants, let's just wait and see and judge him over the course of the season, then you might be able to say which would have been the better option.
And Moron, if most of us had £9m we probably would have gone for neither of them, Dempsey doesn't have many fans on here (I rate him but anyway) and Borini is something of an unknown. It's not a decisive thing that one is better than the other, it can only be judged over the course of the season and maybe even more fairly, over the course of a career - Borini's is still in it's infancy.