Emule, Azureus, Shareaza are all good clients providing access to any files you could ever want. I find the advantage with apps like Emule and Azureus, they actually reward uploaders, so it reduces the leecher factor.

Bitcomet is another good torrent client, although it’s not open source.

I don’t actually think the learning curve is that high for these types of apps. I mean for emule, it’s simply a matter of selecting a ed2k server with a high number of users and files (razorback 2.0 is a good one). And connecting to kad. Although emule can be slow at times, the more users that come and share the faster it will be for everyone. If you don’t share you don’t gain reward points. Bittorrent uses a tit for tat system, which effectively does the same thing.

you get a bunch of bad users in a torrent swarm, then the whole swarm will die out as people leave it.

The RIAA/MPAA knows it can’t shut down open source projects, thats why it’s only targeting registered companies. Like the article says, they are actually helping us by moving people onto open source based p2p apps.