No, NO, do not do this! People buy Edwardians for the original elegance & atmosphere. See real estate pics online. The "great room", as you suggest, is trendy right now and for some folks it is just what they need. However this one-room design is generally found in the newer homes with a more casual feel, esp. vacation homes.
Not only will you not get your money back, but you DECREASING your chances of selling at an appropriate price.