The homburg is more formal than the fedora. I decided that my black Borsalino Continental was too formal for a notched-lapel suit -- it would be better with double breasted/peaked lapels or, of course, tuxedo. But I wanted to wear it with the dark suit, so I pinched the crown and bent the sides up slightly, reducing its formality a bit -- but it is still an elegant formal hat, to be worn with a pocket square and a plain tie.