You receive the user agent identifier after having connected, - but it's not that hard anyway. Just some tiny changes to ManagedDownloader.java and there you are. - The question is, whether this will be so much of an improvement.

I've got to admit I was quite skeptic towards Gnucleus / Morpheus ultrapeers, but as it shows, they aren't as bad as you might think. Although I have the impression LimeWire ultrapeers are better Gnucleus/Morpheus ultrapeers work well enough.