well.. you already have good conditioning.. to drop that much weight will surely be muscle.. at 5'9 you will be "stringy" as a middleweight.. remember that some will be 5'6 or so and the same weight.. they will "outsize" you pretty dramatically..
i hate to see guys trying to hit a class.. go by what looks best.. if you look great at 191 then so be it.. the only time i can see dropping a class is when you are within mere pounds of the limit.. but i can tell ya i highly doubt you will be at your best at a middle weight.. you hold alot of muscle.. take advantage of it..