personally I dont see the 85L as a lens that you have to question whether you need it or not.
basically, every picture I see with one looks more or less the same. it's not a bad look, but it is a look. I think if you do weddings then it's almost a necessity because people expect it. maybe some studio portraiture is the same way. if you, for some reason, need that look then make a trade. if not then sell your 24L and buy a good normal/wide.