@NJS I think it does not work against you especially if you ask the person if you can mention them in your application, however, I do believe that it is not a game changer, it does not distinguish you from other people applying to the same firm. So I would make sure that the person you mention wants to be mentioned and you think they can have a say in putting you through the different stages of the applications, which is very unlikely most of the time. This is just my opinion though!
Good luck with everything!