I have played without nails for 41 years, and am pleased with the sound I can get using flesh only. It took a long time to develop technique that I was satisfied with, and there wasn't much advice for me early on when I was figuring things out on my own. It's nice that Rob has devoted a web site to this now, and it would have helped me progress more rapidly if I would have had that encouragement and explanation.
The tone I can get is pretty nice, and even with just flesh, you can produce everything from warm to bright once you have developed the technique. I play with a straight wrist, allowed to arch down towards the strings, and angle the arm to play off the left side of the fingers. For a brighter tone, I reduce the arm angle so the attack is more from the center of the finger pads. Either way, it is kind of a "ballistic" attack where the finger makes contact with the string, pushing down and through to produce the tone. Maybe unconventional, I don't know, but it works for me.
I just never had the ability to develop or keep good nails, and I sure didn't want to stop playing the CG, so as they say, "Necessity is the mother of invention."
Happy playing to all, nails or not!
2008 Jose Ramirez 2NE
"So Much Music, So Little Time."