I have met several noders IRL, best guess was 6. Sarcasmo insisted that I call him Sarcasmo, though he did tell me his real name. He also made me promise not to tell anyone... I tried, but I hid it in one of my nodes, but I can't remember where. Easter Egg Hunt!
When I talk with noders, I tend to use some form of their nick. But when I have to say something with weight, i'll take a note from mothers and use their real name. It's more personal, and well, it's (usually) more a part of who we are. Studies have shown that hearing one's name releases anti-stress chemicals in the brain, both improving our moods and making us more receptive to the speaker. I know it makes me feel good when someone who probably doesn't remember me does greet me with my name.
At the Florida New Year's bash, 2002, whilst inder the unfluence, I continually called Phyllis_Stein by the first half of his nick. Now, I don't think most guys would appreciate if you called them "Phyllis" all night. He finally flat out asked me to stop calling him that, and reminded me what his real name is.
Names are power. Be careful who you empower.