So, you're saying you can trust a client because it's open-source? bull#@&%. Do you trust Morpheus? Morpheus, the currently most popular Gnutella client, by far, which is also open-source, and a clone of another popular open source client, has done more to bring down the Gnutella network than the RIAA or any government agency to date. This is the sort of bullcrap that open-source clients add to the network. I would rather not see a repeat of the current situation again. Stay closed-source!

Not to mention that no form of security can be built-in to any open-source clients.

IMHO, the only thing open-source does is allow creeps to rip off someone else's code, change a few things, such as links and ads (either ripping them out, adding some in, or replacing the old ones with new ones so the new company gets the money instead), and stick their name on it, and more often than not, the new clients don't care about the health of the network... Think Morpheus, Freewire, etc.