I was a Gnucleus user previously. Got sick and tired of its constant crashes. I used to use Limewire occasionally, if I wanted to leave it running overnight or something, because it didn't crash as often as Gnucleus. Eventually registered for Limewire Pro, and lo'n'behold just as I do that Gnucleus 1.8.4 comes out and it's got to be the most stable release of Gnucleus I have ever experienced. I can keep it running for days on end, the only reason to stop it is when I have to reboot my machine for some reason.

It's as stable as Limewire is. Plus it doesn't use as much CPU power as Limewire does, so it scales better. It doesn't suffer from the resume downloads from zero bug of Limewire. And best of all, it's free, GNU source-code software.