I'm currently collecting some statistical data for gnucleus ultrapeers. As it seems your horizon is smaller than with LimeWire ultrapeers, - although you can do some funny things with gnucleus ultrapeers you can't do with LimeWire.

Since Gnucleus ultrapeers don't seem to pass on many ultrapeer pongs to their leaf clients (those are used to create horizon statistics in most clients), they appear to be a lot worse than they really are.

For example you can spam Gnucleus ultrapeers with greedy queries ('mp3', 'avi', etc.) and while LimeWire ultrapeers would soon drop the connection, Gnucleus will keep on routing results for minutes (taking the ultrapeer out for the rest of its leaf clients completely).