Processes similar to Ultrapeer are utilized by other file-sharing networks, such as by the protocol now in use by Kazaa or Morpheus; they are very effective and allow for very efficent peer networks. At the present moment, however I find it an inconvience. I think, that you should also have control options for users to utilize the current Gnutella infastructure while you develop this model further (at the very least this should be done for the Pro customers!).